CDI

Contents

1  Introduction

CDI is an Interface to access Climate and forecast model Data. The interface is independent from a specific data format and has a C and Fortran API. CDI was developed for a fast and machine independent access to GRIB and NetCDF datasets with the same interface. The local MPI-MET data formats SERVICE, EXTRA and IEG are also supported.

1.1  Building from sources

This section describes how to build the CDI library from the sources on a UNIX system. CDI is using the GNU configure and build system to compile the source code. The only requirement is a working ANSI C99 compiler.

First go to the download page (https://code.mpimet.mpg.de/projects/cdi/files) to get the latest distribution, if you do not already have it.

To take full advantage of CDI’s features the following additional libraries should be installed:

• Unidata NetCDF library (http://www.unidata.ucar.edu/packages/netcdf) version 3 or higher. This is needed to read/write NetCDF files with CDI.
• ECMWF ecCodes library (https://software.ecmwf.int/wiki/display/ECC/ecCodes+Home) version 2.3.0 or higher. This library is needed to encode/decode GRIB2 records with CDI.

1.1.1  Compilation

Compilation is now done by performing the following steps:

1. Unpack the archive, if you haven’t already done that:

       
            gunzip cdi-$VERSION.tar.gz    # uncompress the archive
            tar xf cdi-$VERSION.tar       # unpack it
            cd cdi-$VERSION
   

2. Run the configure script:

       
            ./configure
   

   Or optionally with NetCDF support:

       
            ./configure --with-netcdf=<NetCDF root directory>
   

   For an overview of other configuration options use

       
            ./configure --help
   

3. Compile the program by running make:

       
            make
   

The software should compile without problems and the CDI library (libcdi.a) should be available in the src directory of the distribution.

1.1.2  Installation

After the compilation of the source code do a make install, possibly as root if the destination permissions require that.

    make install

The library is installed into the directory <prefix>/lib. The C and Fortran include files are installed into the directory <prefix>/include. <prefix> defaults to /usr/local but can be changed with the --prefix option of the configure script.

2  File Formats

2.1  GRIB

GRIB [GRIB] (GRIdded Binary) is a standard format designed by the World Meteorological Organization (WMO) to support the efficient transmission and storage of gridded meteorological data.

A GRIB record consists of a series of header sections, followed by a bitstream of packed data representing one horizontal grid of data values. The header sections are intended to fully describe the data included in the bitstream, specifying information such as the parameter, units, and precision of the data, the grid system and level type on which the data is provided, and the date and time for which the data are valid.

Non-numeric descriptors are enumerated in tables, such that a 1-byte code in a header section refers to a unique description. The WMO provides a standard set of enumerated parameter names and level types, but the standard also allows for the definition of locally used parameters and geometries. Any activity that generates and distributes GRIB records must also make their locally defined GRIB tables available to users.

The GRIB records must be sorted by time to be able to read them correctly with CDI.

CDI does not support the full GRIB standard. The following data representation and level types are implemented:

2.1.1  GRIB edition 1

GRIB1 is implemented in CDI as an internal library and enabled per default. The internal GRIB1 library is called CGRIBEX. This is a lightweight version of the ECMWF GRIBEX library. CGRIBEX is written in ANSI C with a portable Fortran interface. The configure option --disable-cgribex will disable the encoding/decoding of GRIB1 records with CGRIBEX.

2.1.2  GRIB edition 2

GRIB2 is available in CDI via the ECMWF ecCodes [ecCodes] library. ecCodes is an external library and not part of CDI. To use GRIB2 with CDI the ecCodes library must be installed before the configuration of the CDI library. Use the configure option --with-eccodes to enable GRIB2 support.

The ecCodes library is also used to encode/decode GRIB1 records if the support for the CGRIBEX library is disabled. This feature is not tested regulary and the status is experimental!

A single GRIB2 message can contain multiple fields. This feature is not supported in CDI!

2.2  NetCDF

NetCDF [NetCDF] (Network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of the interface. The NetCDF library also defines a machine-independent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data.

CDI only supports the classic data model of NetCDF and arrays up to 4 dimensions. These dimensions should only be used by the horizontal and vertical grid and the time. The NetCDF attributes should follow the GDT, COARDS or CF Conventions.

NetCDF is an external library and not part of CDI. To use NetCDF with CDI the NetCDF library must be installed before the configuration of the CDI library. Use the configure option --with-netcdf to enable NetCDF support (see Build).

2.3  SERVICE

SERVICE is the binary exchange format of the atmospheric general circulation model ECHAM [ECHAM]. It has a header section with 8 integer values followed by the data section. The header and the data section have the standard Fortran blocking for binary data records. A SERVICE record can have an accuracy of 4 or 8 bytes and the byteorder can be little or big endian. In CDI the accuracy of the header and data section must be the same. The following Fortran code example can be used to read a SERVICE record with an accuracy of 4 bytes:

The constants mlon and mlat must be greater or equal than nlon and nlat. The meaning of the variables are:

  

SERVICE is implemented in CDI as an internal library and enabled per default. The configure option --disable-service will disable the support for the SERVICE format.

2.4  EXTRA

EXTRA is the standard binary output format of the ocean model MPIOM [MPIOM]. It has a header section with 4 integer values followed by the data section. The header and the data section have the standard Fortran blocking for binary data records. An EXTRA record can have an accuracy of 4 or 8 bytes and the byteorder can be little or big endian. In CDI the accuracy of the header and data section must be the same. The following Fortran code example can be used to read an EXTRA record with an accuracy of 4 bytes:

The constant msize must be greater or equal than nsize. The meaning of the variables are:

  

EXTRA is implemented in CDI as an internal library and enabled per default. The configure option --disable-extra will disable the support for the EXTRA format.

2.5  IEG

IEG is the standard binary output format of the regional model REMO [REMO]. It is simple an unpacked GRIB edition 1 format. The product and grid description sections are coded with 4 byte integer values and the data section can have 4 or 8 byte IEEE floating point values. The header and the data section have the standard Fortran blocking for binary data records. The IEG format has a fixed size of 100 for the vertical coordinate table. That means it is not possible to store more than 50 model levels with this format. CDI supports only data on Gaussian and LonLat grids for the IEG format.

IEG is implemented in CDI as an internal library and enabled per default. The configure option --disable-ieg will disable the support for the IEG format.

3  Use of the CDI Library

This chapter provides templates of common sequences of CDI calls needed for common uses. For clarity only the names of routines are used. Declarations and error checking were omitted. Statements that are typically invoked multiple times were indented and ... is used to represent arbitrary sequences of other statements. Full parameter lists are described in later chapters.

Complete examples for write, read and copy a dataset with CDI can be found in Appendix B.

3.1  Creating a dataset

Here is a typical sequence of CDI calls used to create a new dataset:

3.2  Reading a dataset

Here is a typical sequence of CDI calls used to read a dataset:

3.3  Compiling and Linking with the CDI library

Details of how to compile and link a program that uses the CDI C or FORTRAN interfaces differ, depending on the operating system, the available compilers, and where the CDI library and include files are installed. Here are examples of how to compile and link a program that uses the CDI library on a Unix platform, so that you can adjust these examples to fit your installation. Every C file that references CDI functions or constants must contain an appropriate include statement before the first such reference:

   #include "cdi.h"

Unless the cdi.h file is installed in a standard directory where C compiler always looks, you must use the -I option when invoking the compiler, to specify a directory where cdi.h is installed, for example:

   cc -c -I/usr/local/cdi/include myprogram.c

Alternatively, you could specify an absolute path name in the include statement, but then your program would not compile on another platform where CDI is installed in a different location.

Unless the CDI library is installed in a standard directory where the linker always looks, you must use the -L and -l options to links an object file that uses the CDI library. For example:

   cc -o myprogram myprogram.o -L/usr/local/cdi/lib -lcdi -lm

Alternatively, you could specify an absolute path name for the library:

   cc -o myprogram myprogram.o -L/usr/local/cdi/lib/libcdi -lm

If the CDI library is using other external libraries, you must add this libraries in the same way. For example with the NetCDF library:

   cc -o myprogram myprogram.o -L/usr/local/cdi/lib -lcdi -lm \
                               -L/usr/local/netcdf/lib -lnetcdf

4  CDI modules

4.1  Dataset functions

This module contains functions to read and write the data. To create a new dataset the output format must be specified with one of the following predefined file format types:

  

CDI_FILETYPE_GRB2 is only available if the CDI library was compiled with ecCodes support and all NetCDF file types are only available if the CDI library was compiled with NetCDF support!

To set the byte order of a binary dataset with the file format type CDI_FILETYPE_SRV, CDI_FILETYPE_EXT or CDI_FILETYPE_IEG use one of the following predefined constants in the call to streamDefByteorder:

  

4.1.1  Create a new dataset: streamOpenWrite

The function streamOpenWrite creates a new datset.

Usage

    int streamOpenWrite(const char *path, int filetype);

 

Result

Upon successful completion streamOpenWrite returns an identifier to the open stream. Otherwise, a negative number with the error status is returned.

Errors

 

Example

Here is an example using streamOpenWrite to create a new NetCDF file named foo.nc for writing:

4.1.2  Open a dataset for reading: streamOpenRead

The function streamOpenRead opens an existing dataset for reading.

Usage

    int streamOpenRead(const char *path);

 

Result

Upon successful completion streamOpenRead returns an identifier to the open stream. Otherwise, a negative number with the error status is returned.

Errors

 

Example

Here is an example using streamOpenRead to open an existing NetCDF file named foo.nc for reading:

4.1.3  Close an open dataset: streamClose

The function streamClose closes an open dataset.

Usage

    void streamClose(int streamID);

 

4.1.4  Get the filetype: streamInqFiletype

The function streamInqFiletype returns the filetype of a stream.

Usage

    int streamInqFiletype(int streamID);

 

Result

streamInqFiletype returns the type of the file format, one of the set of predefined CDI file format types. The valid CDI file format types are CDI_FILETYPE_GRB, CDI_FILETYPE_GRB2, CDI_FILETYPE_NC, CDI_FILETYPE_NC2, CDI_FILETYPE_NC4, CDI_FILETYPE_NC4C, CDI_FILETYPE_NC5, CDI_FILETYPE_SRV, CDI_FILETYPE_EXT and CDI_FILETYPE_IEG.

4.1.5  Define the byte order: streamDefByteorder

The function streamDefByteorder defines the byte order of a binary dataset with the file format type CDI_FILETYPE_SRV, CDI_FILETYPE_EXT or CDI_FILETYPE_IEG.

Usage

    void streamDefByteorder(int streamID, int byteorder);

 

4.1.6  Get the byte order: streamInqByteorder

The function streamInqByteorder returns the byte order of a binary dataset with the file format type CDI_FILETYPE_SRV, CDI_FILETYPE_EXT or CDI_FILETYPE_IEG.

Usage

    int streamInqByteorder(int streamID);

 

Result

streamInqByteorder returns the type of the byte order. The valid CDI byte order types are CDI_BIGENDIAN and CDI_LITTLEENDIAN

4.1.7  Define the variable list: streamDefVlist

The function streamDefVlist defines the variable list of a stream.

To safeguard against errors by modifying the wrong vlist object, this function makes the passed vlist object immutable. All further vlist changes have to use the vlist object returned by streamInqVlist().

Usage

    void streamDefVlist(int streamID, int vlistID);

 

4.1.8  Get the variable list: streamInqVlist

The function streamInqVlist returns the variable list of a stream.

Usage

    int streamInqVlist(int streamID);

 

Result

streamInqVlist returns an identifier to the variable list.

4.1.9  Define a timestep: streamDefTimestep

The function streamDefTimestep defines a timestep of a stream by the identifier tsID. The identifier tsID is the timestep index starting at 0 for the first timestep. Before calling this function the functions taxisDefVdate and taxisDefVtime should be used to define the timestamp for this timestep. All calls to write the data refer to this timestep.

Usage

    int streamDefTimestep(int streamID, int tsID);

 

Result

streamDefTimestep returns the number of expected records of the timestep.

4.1.10  Get timestep information: streamInqTimestep

The function streamInqTimestep sets the next timestep to the identifier tsID. The identifier tsID is the timestep index starting at 0 for the first timestep. After a call to this function the functions taxisInqVdate and taxisInqVtime can be used to read the timestamp for this timestep. All calls to read the data refer to this timestep.

Usage

    int streamInqTimestep(int streamID, int tsID);

 

Result

streamInqTimestep returns the number of records of the timestep or 0, if the end of the file is reached.

4.1.11  Write a variable: streamWriteVar

The function streamWriteVar writes the values of one time step of a variable to an open dataset. The values are converted to the external data type of the variable, if necessary.

Usage

    void streamWriteVar(int streamID, int varID, const double *data, size_t nmiss);

 

4.1.12  Write a variable: streamWriteVarF

The function streamWriteVarF writes the values of one time step of a variable to an open dataset. The values are converted to the external data type of the variable, if necessary.

Usage

    void streamWriteVarF(int streamID, int varID, const float *data, size_t nmiss);

 

4.1.13  Write a horizontal slice of a variable: streamWriteVarSlice

The function streamWriteVarSlice writes the values of a horizontal slice of a variable to an open dataset. The values are converted to the external data type of the variable, if necessary.

Usage

    void streamWriteVarSlice(int streamID, int varID, int levelID, const double *data,
                             size_t nmiss);

 

4.1.14  Write a horizontal slice of a variable: streamWriteVarSliceF

The function streamWriteVarSliceF writes the values of a horizontal slice of a variable to an open dataset. The values are converted to the external data type of the variable, if necessary.

Usage

    void streamWriteVarSliceF(int streamID, int varID, int levelID, const float *data,
                              size_t nmiss);

 

4.1.15  Read a variable: streamReadVar

The function streamReadVar reads all the values of one time step of a variable from an open dataset.

Usage

    void streamReadVar(int streamID, int varID, double *data, size_t *nmiss);

 

4.1.16  Read a variable: streamReadVarF

The function streamReadVar reads all the values of one time step of a variable from an open dataset.

Usage

    void streamReadVar(int streamID, int varID, float *data, size_t *nmiss);

 

4.1.17  Read a horizontal slice of a variable: streamReadVarSlice

The function streamReadVarSlice reads all the values of a horizontal slice of a variable from an open dataset.

Usage

    void streamReadVarSlice(int streamID, int varID, int levelID, double *data,
                            size_t *nmiss);

 

4.1.18  Read a horizontal slice of a variable: streamReadVarSliceF

The function streamReadVarSliceF reads all the values of a horizontal slice of a variable from an open dataset.

Usage

    void streamReadVarSliceF(int streamID, int varID, int levelID, float *data,
                             size_t *nmiss);

 

4.2  Variable list functions

This module contains functions to handle a list of variables. A variable list is a collection of all variables of a dataset.

4.2.1  Create a variable list: vlistCreate

Usage

    int vlistCreate(void);

Example

Here is an example using vlistCreate to create a variable list and add a variable with vlistDefVar.

4.2.2  Destroy a variable list: vlistDestroy

Usage

    void vlistDestroy(int vlistID);

 

4.2.3  Copy a variable list: vlistCopy

The function vlistCopy copies all entries from vlistID1 to vlistID2.

Usage

    void vlistCopy(int vlistID2, int vlistID1);

 

4.2.4  Duplicate a variable list: vlistDuplicate

The function vlistDuplicate duplicates the variable list from vlistID1.

Usage

    int vlistDuplicate(int vlistID);

 

Result

vlistDuplicate returns an identifier to the duplicated variable list.

4.2.5  Concatenate two variable lists: vlistCat

Concatenate the variable list vlistID1 at the end of vlistID2.

Usage

    void vlistCat(int vlistID2, int vlistID1);

 

4.2.6  Copy some entries of a variable list: vlistCopyFlag

The function vlistCopyFlag copies all entries with a flag from vlistID1 to vlistID2.

Usage

    void vlistCopyFlag(int vlistID2, int vlistID1);

 

4.2.7  Number of variables in a variable list: vlistNvars

The function vlistNvars returns the number of variables in the variable list vlistID.

Usage

    int vlistNvars(int vlistID);

 

Result

vlistNvars returns the number of variables in a variable list.

4.2.8  Number of grids in a variable list: vlistNgrids

The function vlistNgrids returns the number of grids in the variable list vlistID.

Usage

    int vlistNgrids(int vlistID);

 

Result

vlistNgrids returns the number of grids in a variable list.

4.2.9  Number of zaxis in a variable list: vlistNzaxis

The function vlistNzaxis returns the number of zaxis in the variable list vlistID.

Usage

    int vlistNzaxis(int vlistID);

 

Result

vlistNzaxis returns the number of zaxis in a variable list.

4.2.10  Define the time axis: vlistDefTaxis

The function vlistDefTaxis defines the time axis of a variable list.

Usage

    void vlistDefTaxis(int vlistID, int taxisID);

 

4.2.11  Get the time axis: vlistInqTaxis

The function vlistInqTaxis returns the time axis of a variable list.

Usage

    int vlistInqTaxis(int vlistID);

 

Result

vlistInqTaxis returns an identifier to the time axis.

4.3  Variable functions

This module contains functions to add new variables to a variable list and to get information about variables from a variable list. To add new variables to a variables list one of the following timestep types must be specified:

  

The default data type is 16 bit for GRIB and 32 bit for all other file format types. To change the data type use one of the following predefined constants:

  

4.3.1  Define a Variable: vlistDefVar

The function vlistDefVar adds a new variable to vlistID.

Usage

    int vlistDefVar(int vlistID, int gridID, int zaxisID, int timetype);

 

Result

vlistDefVar returns an identifier to the new variable.

Example

Here is an example using vlistCreate to create a variable list and add a variable with vlistDefVar.

4.3.2  Get the Grid ID of a Variable: vlistInqVarGrid

The function vlistInqVarGrid returns the grid ID of a Variable.

Usage

    int vlistInqVarGrid(int vlistID, int varID);

 

Result

vlistInqVarGrid returns the grid ID of the Variable.

4.3.3  Get the Zaxis ID of a Variable: vlistInqVarZaxis

The function vlistInqVarZaxis returns the zaxis ID of a variable.

Usage

    int vlistInqVarZaxis(int vlistID, int varID);

 

Result

vlistInqVarZaxis returns the zaxis ID of the variable.

4.3.4  Get the timestep type of a Variable: vlistInqVarTsteptype

The function vlistInqVarTsteptype returns the timestep type of a Variable.

Usage

    int vlistInqVarTsteptype(int vlistID, int varID);

 

Result

vlistInqVarTsteptype returns the timestep type of the Variable, one of the set of predefined CDI timestep types. The valid CDI timestep types are TSTEP_INSTANT, TSTEP_ACCUM, TSTEP_AVG, TSTEP_MAX, TSTEP_MIN and TSTEP_SD.

4.3.5  Define the code number of a Variable: vlistDefVarCode

The function vlistDefVarCode defines the code number of a variable.

Usage

    void vlistDefVarCode(int vlistID, int varID, int code);

 

4.3.6  Get the Code number of a Variable: vlistInqVarCode

The function vlistInqVarCode returns the code number of a variable.

Usage

    int vlistInqVarCode(int vlistID, int varID);

 

Result

vlistInqVarCode returns the code number of the variable.

4.3.7  Define the data type of a Variable: vlistDefVarDatatype

The function vlistDefVarDatatype defines the data type of a variable.

Usage

    void vlistDefVarDatatype(int vlistID, int varID, int datatype);

 

4.3.8  Get the data type of a Variable: vlistInqVarDatatype

The function vlistInqVarDatatype returns the data type of a variable.

Usage

    int vlistInqVarDatatype(int vlistID, int varID);

 

Result

vlistInqVarDatatype returns an identifier to the data type of the variable. The valid CDI data types are CDI_DATATYPE_PACK8, CDI_DATATYPE_PACK16, CDI_DATATYPE_PACK24, CDI_DATATYPE_FLT32, CDI_DATATYPE_FLT64, CDI_DATATYPE_INT8, CDI_DATATYPE_INT16 and CDI_DATATYPE_INT32.

4.3.9  Define the missing value of a Variable: vlistDefVarMissval

The function vlistDefVarMissval defines the missing value of a variable.

Usage

    void vlistDefVarMissval(int vlistID, int varID, double missval);

 

4.3.10  Get the missing value of a Variable: vlistInqVarMissval

The function vlistInqVarMissval returns the missing value of a variable.

Usage

    double vlistInqVarMissval(int vlistID, int varID);

 

Result

vlistInqVarMissval returns the missing value of the variable.

4.4  Key attributes

Attributes are metadata used to describe variables or a data set. CDI distinguishes between key attributes and user attributes. User defined attributes are described in the next chapter.

Key attributes are attributes that are interpreted by CDI. An example is the name or the units of a variable.

Key attributes can be defined for data variables and coordinate variables Use the variable ID or one of the following identifiers for the coordinates:

  

Some keys like name and units can be used for all variables. Other keys are very special and should only be used for certain variables. The user is also responsible for the data type of the key.

CDI supports string, integer, floating point and byte array key attributes. The following key attributes are available:

String keys

  

Integer keys

  

Floating point keys

Byte array keys

  

4.4.1  Define a string from a key: cdiDefKeyString

The function cdiDefKeyString defines a text string from a key.

Usage

    int cdiDefKeyString(int cdiID, int varID, int key, const char *string);

 

Result

cdiDefKeyString returns CDI_NOERR if OK.

Example

Here is an example using cdiDefKeyString to define the name of a variable:

4.4.2  Get a string from a key: cdiInqKeyString

The function cdiInqKeyString gets a text string from a key.

Usage

    int cdiInqKeyString(int cdiID, int varID, int key, char *string, int *length);

 

Result

cdiInqKeyString returns CDI_NOERR if key is available.

Example

Here is an example using cdiInqKeyString to get the name of the first variable:

4.4.3  Define an integer value from a key: cdiDefKeyInt

The function cdiDefKeyInt defines an integer value from a key.

Usage

    int cdiDefKeyInt(int cdiID, int varID, int key, int value);

 

Result

cdiDefKeyInt returns CDI_NOERR if OK.

4.4.4  Get an integer value from a key: cdiInqKeyInt

The function cdiInqKeyInt gets an integer value from a key.

Usage

    int cdiInqKeyInt(int cdiID, int varID, int key, int *value);

 

Result

cdiInqKeyInt returns CDI_NOERR if key is available.

4.4.5  Define a floating point value from a key: cdiDefKeyFloat

The function cdiDefKeyFloat defines a CDI floating point value from a key.

Usage

    int cdiDefKeyFloat(int cdiID, int varID, int key, double value);

 

Result

cdiDefKeyFloat returns CDI_NOERR if OK.

4.4.6  Get a floating point value from a key: cdiInqKeyFloat

The function cdiInqKeyFloat gets a floating point value from a key.

Usage

    int cdiInqKeyFloat(int cdiID, int varID, int key, double *value);

 

Result

cdiInqKeyFloat returns CDI_NOERR if key is available.

4.4.7  Define a byte array from a key: cdiDefKeyBytes

The function cdiDefKeyBytes defines a byte array from a key.

Usage

    int cdiDefKeyBytes(int cdiID, int varID, int key, const unsigned char *bytes,
                       int length);

 

Result

cdiDefKeyBytes returns CDI_NOERR if OK.

4.4.8  Get a byte array from a key: cdiInqKeyBytes

The function cdiInqKeyBytes gets a byte array from a key.

Usage

    int cdiInqKeyBytes(int cdiID, int varID, int key, unsigned char *bytes, int *length);

 

Result

cdiInqKeyBytes returns CDI_NOERR if key is available.

4.5  User attributes

Attributes are metadata used to describe variables or a data set. CDI distinguishes between key attributes and user attributes. Key attributes are described in the last chapter.

User defined attributes are additional attributes that are not interpreted by CDI. These attributes are only available for NetCDF datasets. Here they correspond to all attributes that are not used by CDI as key attributes.

A user defined attribute has a variable to which it is assigned, a name, a type, a length, and a sequence of one or more values. The attributes have to be defined after the variable is created and before the variables list is associated with a stream.

It is also possible to have attributes that are not associated with any variable. These are called global attributes and are identified by using CDI_GLOBAL as a variable pseudo-ID. Global attributes are usually related to the dataset as a whole.

CDI supports integer, floating point and text attributes. The data types are defined by the following predefined constants:

  

4.5.1  Get number of attributes: cdiInqNatts

The function cdiInqNatts gets the number of attributes assigned to this variable.

Usage

    int cdiInqNatts(int cdiID, int varID, int *nattsp);

 

4.5.2  Get information about an attribute: cdiInqAtt

The function cdiInqAtt gets information about an attribute.

Usage

    int cdiInqAtt(int cdiID, int varID, int attnum, char *name, int *typep, int *lenp);

 

4.5.3  Define a text attribute: cdiDefAttTxt

The function cdiDefAttTxt defines a text attribute.

Usage

    int cdiDefAttTxt(int cdiID, int varID, const char *name, int len, const char *tp);

 

Example

Here is an example using cdiDefAttTxt to define the attribute ”description”:

4.5.4  Get the value(s) of a text attribute: cdiInqAttTxt

The function cdiInqAttTxt gets the values(s) of a text attribute.

Usage

    int cdiInqAttTxt(int cdiID, int varID, const char *name, int mlen, char *tp);

 

4.5.5  Define an integer attribute: cdiDefAttInt

The function cdiDefAttInt defines an integer attribute.

Usage

    int cdiDefAttInt(int cdiID, int varID, const char *name, int type, int len,
                     const int *ip);

 

4.5.6  Get the value(s) of an integer attribute: cdiInqAttInt

The function cdiInqAttInt gets the values(s) of an integer attribute.

Usage

    int cdiInqAttInt(int cdiID, int varID, const char *name, int mlen, int *ip);

 

4.5.7  Define a floating point attribute: cdiDefAttFlt

The function cdiDefAttFlt defines a floating point attribute.

Usage

    int cdiDefAttFlt(int cdiID, int varID, const char *name, int type, int len,
                     const double *dp);

 

4.5.8  Get the value(s) of a floating point attribute: cdiInqAttFlt

The function cdiInqAttFlt gets the values(s) of a floating point attribute.

Usage

    int cdiInqAttFlt(int cdiID, int varID, const char *name, int mlen, double *dp);

 

4.6  Grid functions

This module contains functions to define a new horizontal Grid and to get information from an existing Grid. A Grid object is necessary to define a variable. The following different Grid types are available:

  

4.6.1  Create a horizontal Grid: gridCreate

The function gridCreate creates a horizontal Grid.

Usage

    int gridCreate(int gridtype, size_t size);

 

Result

gridCreate returns an identifier to the Grid.

Example

Here is an example using gridCreate to create a regular lon/lat Grid:

4.6.2  Destroy a horizontal Grid: gridDestroy

Usage

    void gridDestroy(int gridID);

 

4.6.3  Duplicate a horizontal Grid: gridDuplicate

The function gridDuplicate duplicates a horizontal Grid.

Usage

    int gridDuplicate(int gridID);

 

Result

gridDuplicate returns an identifier to the duplicated Grid.

4.6.4  Get the type of a Grid: gridInqType

The function gridInqType returns the type of a Grid.

Usage

    int gridInqType(int gridID);

 

Result

gridInqType returns the type of the grid, one of the set of predefined CDI grid types. The valid CDI grid types are GRID_GENERIC, GRID_LONLAT, GRID_GAUSSIAN, GRID_PROJECTION, GRID_SPECTRAL, GRID_GME, GRID_CURVILINEAR and GRID_UNSTRUCTURED.

4.6.5  Get the size of a Grid: gridInqSize

The function gridInqSize returns the size of a Grid.

Usage

    size_t gridInqSize(int gridID);

 

Result

gridInqSize returns the number of grid points of a Grid.

4.6.6  Define the number of values of a X-axis: gridDefXsize

The function gridDefXsize defines the number of values of a X-axis.

Usage

    void gridDefXsize(int gridID, size_t xsize);

 

4.6.7  Get the number of values of a X-axis: gridInqXsize

The function gridInqXsize returns the number of values of a X-axis.

Usage

    size_t gridInqXsize(int gridID);

 

Result

gridInqXsize returns the number of values of a X-axis.

4.6.8  Define the number of values of a Y-axis: gridDefYsize

The function gridDefYsize defines the number of values of a Y-axis.

Usage

    void gridDefYsize(int gridID, size_t ysize);

 

4.6.9  Get the number of values of a Y-axis: gridInqYsize

The function gridInqYsize returns the number of values of a Y-axis.

Usage

    size_t gridInqYsize(int gridID);

 

Result

gridInqYsize returns the number of values of a Y-axis.

4.6.10  Define the number of parallels between a pole and the equator: gridDefNP

The function gridDefNP defines the number of parallels between a pole and the equator of a Gaussian grid.

Usage

    void gridDefNP(int gridID, int np);

 

4.6.11  Get the number of parallels between a pole and the equator: gridInqNP

The function gridInqNP returns the number of parallels between a pole and the equator of a Gaussian grid.

Usage

    int gridInqNP(int gridID);

 

Result

gridInqNP returns the number of parallels between a pole and the equator.

4.6.12  Define the values of a X-axis: gridDefXvals

The function gridDefXvals defines all values of the X-axis.

Usage

    void gridDefXvals(int gridID, const double *xvals);

 

4.6.13  Get all values of a X-axis: gridInqXvals

The function gridInqXvals returns all values of the X-axis.

Usage

    size_t gridInqXvals(int gridID, double *xvals);

 

Result

Upon successful completion gridInqXvals returns the number of values and the values are stored in xvals. Otherwise, 0 is returned and xvals is empty.

4.6.14  Define the values of a Y-axis: gridDefYvals

The function gridDefYvals defines all values of the Y-axis.

Usage

    void gridDefYvals(int gridID, const double *yvals);

 

4.6.15  Get all values of a Y-axis: gridInqYvals

The function gridInqYvals returns all values of the Y-axis.

Usage

    size_t gridInqYvals(int gridID, double *yvals);

 

Result

Upon successful completion gridInqYvals returns the number of values and the values are stored in yvals. Otherwise, 0 is returned and yvals is empty.

4.6.16  Define the bounds of a X-axis: gridDefXbounds

The function gridDefXbounds defines all bounds of the X-axis.

Usage

    void gridDefXbounds(int gridID, const double *xbounds);

 

4.6.17  Get the bounds of a X-axis: gridInqXbounds

The function gridInqXbounds returns the bounds of the X-axis.

Usage

    size_t gridInqXbounds(int gridID, double *xbounds);

 

Result

Upon successful completion gridInqXbounds returns the number of bounds and the bounds are stored in xbounds. Otherwise, 0 is returned and xbounds is empty.

4.6.18  Define the bounds of a Y-axis: gridDefYbounds

The function gridDefYbounds defines all bounds of the Y-axis.

Usage

    void gridDefYbounds(int gridID, const double *ybounds);

 

4.6.19  Get the bounds of a Y-axis: gridInqYbounds

The function gridInqYbounds returns the bounds of the Y-axis.

Usage

    size_t gridInqYbounds(int gridID, double *ybounds);

 

Result

Upon successful completion gridInqYbounds returns the number of bounds and the bounds are stored in ybounds. Otherwise, 0 is returned and ybounds is empty.

4.7  Z-axis functions

This section contains functions to define a new vertical Z-axis and to get information from an existing Z-axis. A Z-axis object is necessary to define a variable. The following different Z-axis types are available:

  

4.7.1  Create a vertical Z-axis: zaxisCreate

The function zaxisCreate creates a vertical Z-axis.

Usage

    int zaxisCreate(int zaxistype, int size);

 

Result

zaxisCreate returns an identifier to the Z-axis.

Example

Here is an example using zaxisCreate to create a pressure level Z-axis:

4.7.2  Destroy a vertical Z-axis: zaxisDestroy

Usage

    void zaxisDestroy(int zaxisID);

 

4.7.3  Get the type of a Z-axis: zaxisInqType

The function zaxisInqType returns the type of a Z-axis.

Usage

    int zaxisInqType(int zaxisID);

 

Result

zaxisInqType returns the type of the Z-axis, one of the set of predefined CDI Z-axis types. The valid CDI Z-axis types are ZAXIS_GENERIC, ZAXIS_SURFACE, ZAXIS_HYBRID, ZAXIS_SIGMA, ZAXIS_PRESSURE, ZAXIS_HEIGHT, ZAXIS_ISENTROPIC, ZAXIS_ALTITUDE, ZAXIS_MEANSEA, ZAXIS_TOA, ZAXIS_SEA_BOTTOM, ZAXIS_ATMOSPHERE, ZAXIS_CLOUD_BASE, ZAXIS_CLOUD_TOP, ZAXIS_ISOTHERM_ZERO, ZAXIS_SNOW, ZAXIS_LAKE_BOTTOM, ZAXIS_SEDIMENT_BOTTOM, ZAXIS_SEDIMENT_BOTTOM_TA, ZAXIS_SEDIMENT_BOTTOM_TW, ZAXIS_MIX_LAYER, ZAXIS_DEPTH_BELOW_SEA and ZAXIS_DEPTH_BELOW_LAND.

4.7.4  Get the size of a Z-axis: zaxisInqSize

The function zaxisInqSize returns the size of a Z-axis.

Usage

    int zaxisInqSize(int zaxisID);

 

Result

zaxisInqSize returns the number of levels of a Z-axis.

4.7.5  Define the levels of a Z-axis: zaxisDefLevels

The function zaxisDefLevels defines the levels of a Z-axis.

Usage

    void zaxisDefLevels(int zaxisID, const double *levels);

 

4.7.6  Get all levels of a Z-axis: zaxisInqLevels

The function zaxisInqLevels returns all levels of a Z-axis.

Usage

    void zaxisInqLevels(int zaxisID, double *levels);

 

Result

zaxisInqLevels saves all levels to the parameter levels.

4.7.7  Get one level of a Z-axis: zaxisInqLevel

The function zaxisInqLevel returns one level of a Z-axis.

Usage

    double zaxisInqLevel(int zaxisID, int levelID);

 

Result

zaxisInqLevel returns the level of a Z-axis.

4.8  T-axis functions

This section contains functions to define a new Time axis and to get information from an existing T-axis. A T-axis object is necessary to define the time axis of a dataset and must be assiged to a variable list using vlistDefTaxis. The following different Time axis types are available:

  

An absolute time axis has the current time to each time step. It can be used without knowledge of the calendar.

A relative time is the time relative to a fixed reference time. The current time results from the reference time and the elapsed interval. The result depends on the used calendar. CDI supports the following calendar types:

  

4.8.1  Create a Time axis: taxisCreate

The function taxisCreate creates a Time axis.

Usage

    int taxisCreate(int taxistype);

 

Result

taxisCreate returns an identifier to the Time axis.

Example

Here is an example using taxisCreate to create a relative T-axis with a standard calendar.

4.8.2  Destroy a Time axis: taxisDestroy

Usage

    void taxisDestroy(int taxisID);

 

4.8.3  Define the reference date: taxisDefRdate

The function taxisDefRdate defines the reference date of a Time axis.

Usage

    void taxisDefRdate(int taxisID, int64_t rdate);

 

4.8.4  Get the reference date: taxisInqRdate

The function taxisInqRdate returns the reference date of a Time axis.

Usage

    int64_t taxisInqRdate(int taxisID);

 

Result

taxisInqRdate returns the reference date.

4.8.5  Define the reference time: taxisDefRtime

The function taxisDefRtime defines the reference time of a Time axis.

Usage

    void taxisDefRtime(int taxisID, int rtime);

 

4.8.6  Get the reference time: taxisInqRtime

The function taxisInqRtime returns the reference time of a Time axis.

Usage

    int taxisInqRtime(int taxisID);

 

Result

taxisInqRtime returns the reference time.

4.8.7  Define the verification date: taxisDefVdate

The function taxisDefVdate defines the verification date of a Time axis.

Usage

    void taxisDefVdate(int taxisID, int64_t vdate);

 

4.8.8  Get the verification date: taxisInqVdate

The function taxisInqVdate returns the verification date of a Time axis.

Usage

    int64_t taxisInqVdate(int taxisID);

 

Result

taxisInqVdate returns the verification date.

4.8.9  Define the verification time: taxisDefVtime

The function taxisDefVtime defines the verification time of a Time axis.

Usage

    void taxisDefVtime(int taxisID, int vtime);

 

4.8.10  Get the verification time: taxisInqVtime

The function taxisInqVtime returns the verification time of a Time axis.

Usage

    int taxisInqVtime(int taxisID);

 

Result

taxisInqVtime returns the verification time.

4.8.11  Define the calendar: taxisDefCalendar

The function taxisDefCalendar defines the calendar of a Time axis.

Usage

    void taxisDefCalendar(int taxisID, int calendar);

 

4.8.12  Get the calendar: taxisInqCalendar

The function taxisInqCalendar returns the calendar of a Time axis.

Usage

    int taxisInqCalendar(int taxisID);

 

Result

taxisInqCalendar returns the type of the calendar, one of the set of predefined CDI calendar types. The valid CDI calendar types are CALENDAR_STANDARD, CALENDAR_PROLEPTIC, CALENDAR_360DAYS, CALENDAR_365DAYS and CALENDAR_366DAYS.

Bibliography

A.  Quick Reference

This appendix provide a brief listing of the C language bindings of the CDI library routines:

cdiDefAttFlt

    int cdiDefAttFlt(int cdiID, int varID, const char *name, int type, int len,
                     const double *dp);

Define a floating point attribute (4.5.7)

cdiDefAttInt

    int cdiDefAttInt(int cdiID, int varID, const char *name, int type, int len,
                     const int *ip);

Define an integer attribute (4.5.5)

cdiDefAttTxt

    int cdiDefAttTxt(int cdiID, int varID, const char *name, int len, const char *tp);

Define a text attribute (4.5.3)

cdiDefKeyBytes

    int cdiDefKeyBytes(int cdiID, int varID, int key, const unsigned char *bytes,
                       int length);

Define a byte array from a key (4.4.7)

cdiDefKeyFloat

    int cdiDefKeyFloat(int cdiID, int varID, int key, double value);

Define a floating point value from a key (4.4.5)

cdiDefKeyInt

    int cdiDefKeyInt(int cdiID, int varID, int key, int value);

Define an integer value from a key (4.4.3)

cdiDefKeyString

    int cdiDefKeyString(int cdiID, int varID, int key, const char *string);

Define a string from a key (4.4.1)

cdiInqAtt

    int cdiInqAtt(int cdiID, int varID, int attnum, char *name, int *typep, int *lenp);

Get information about an attribute (4.5.2)

cdiInqAttFlt

    int cdiInqAttFlt(int cdiID, int varID, const char *name, int mlen, double *dp);

Get the value(s) of a floating point attribute (4.5.8)

cdiInqAttInt

    int cdiInqAttInt(int cdiID, int varID, const char *name, int mlen, int *ip);

Get the value(s) of an integer attribute (4.5.6)

cdiInqAttTxt

    int cdiInqAttTxt(int cdiID, int varID, const char *name, int mlen, char *tp);

Get the value(s) of a text attribute (4.5.4)

cdiInqKeyBytes

    int cdiInqKeyBytes(int cdiID, int varID, int key, unsigned char *bytes, int *length);

Get a byte array from a key (4.4.8)

cdiInqKeyFloat

    int cdiInqKeyFloat(int cdiID, int varID, int key, double *value);

Get a floating point value from a key (4.4.6)

cdiInqKeyInt

    int cdiInqKeyInt(int cdiID, int varID, int key, int *value);

Get an integer value from a key (4.4.4)

cdiInqKeyString

    int cdiInqKeyString(int cdiID, int varID, int key, char *string, int *length);

Get a string from a key (4.4.2)

cdiInqNatts

    int cdiInqNatts(int cdiID, int varID, int *nattsp);

Get number of attributes (4.5.1)

gridCreate

    int gridCreate(int gridtype, size_t size);

Create a horizontal Grid (4.6.1)

gridDefNP

    void gridDefNP(int gridID, int np);

Define the number of parallels between a pole and the equator (4.6.10)

gridDefXbounds

    void gridDefXbounds(int gridID, const double *xbounds);

Define the bounds of a X-axis (4.6.16)

gridDefXsize

    void gridDefXsize(int gridID, size_t xsize);

Define the number of values of a X-axis (4.6.6)

gridDefXvals

    void gridDefXvals(int gridID, const double *xvals);

Define the values of a X-axis (4.6.12)

gridDefYbounds

    void gridDefYbounds(int gridID, const double *ybounds);

Define the bounds of a Y-axis (4.6.18)

gridDefYsize

    void gridDefYsize(int gridID, size_t ysize);

Define the number of values of a Y-axis (4.6.8)

gridDefYvals

    void gridDefYvals(int gridID, const double *yvals);

Define the values of a Y-axis (4.6.14)

gridDestroy

    void gridDestroy(int gridID);

Destroy a horizontal Grid (4.6.2)

gridDuplicate

    int gridDuplicate(int gridID);

Duplicate a horizontal Grid (4.6.3)

gridInqNP

    int gridInqNP(int gridID);

Get the number of parallels between a pole and the equator (4.6.11)

gridInqSize

    size_t gridInqSize(int gridID);

Get the size of a Grid (4.6.5)

gridInqType

    int gridInqType(int gridID);

Get the type of a Grid (4.6.4)

gridInqXbounds

    size_t gridInqXbounds(int gridID, double *xbounds);

Get the bounds of a X-axis (4.6.17)

gridInqXsize

    size_t gridInqXsize(int gridID);

Get the number of values of a X-axis (4.6.7)

gridInqXvals

    size_t gridInqXvals(int gridID, double *xvals);

Get all values of a X-axis (4.6.13)

gridInqYbounds

    size_t gridInqYbounds(int gridID, double *ybounds);

Get the bounds of a Y-axis (4.6.19)

gridInqYsize

    size_t gridInqYsize(int gridID);

Get the number of values of a Y-axis (4.6.9)

gridInqYvals

    size_t gridInqYvals(int gridID, double *yvals);

Get all values of a Y-axis (4.6.15)

streamClose

    void streamClose(int streamID);

Close an open dataset (4.1.3)

streamDefByteorder

    void streamDefByteorder(int streamID, int byteorder);

Define the byte order (4.1.5)

streamDefRecord

    void streamDefRecord(int streamID, int varID, int levelID);

Define the next record (??)

streamDefTimestep

    int streamDefTimestep(int streamID, int tsID);

Define a timestep (4.1.9)

streamDefVlist

    void streamDefVlist(int streamID, int vlistID);

Define the variable list (4.1.7)

streamInqByteorder

    int streamInqByteorder(int streamID);

Get the byte order (4.1.6)

streamInqFiletype

    int streamInqFiletype(int streamID);

Get the filetype (4.1.4)

streamInqTimestep

    int streamInqTimestep(int streamID, int tsID);

Get timestep information (4.1.10)

streamInqVlist

    int streamInqVlist(int streamID);

Get the variable list (4.1.8)

streamOpenRead

    int streamOpenRead(const char *path);

Open a dataset for reading (4.1.2)

streamOpenWrite

    int streamOpenWrite(const char *path, int filetype);

Create a new dataset (4.1.1)

streamReadVar

    void streamReadVar(int streamID, int varID, double *data, size_t *nmiss);

Read a variable (4.1.15)

streamReadVarF

    void streamReadVar(int streamID, int varID, float *data, size_t *nmiss);

Read a variable (4.1.16)

streamReadVarSlice

    void streamReadVarSlice(int streamID, int varID, int levelID, double *data,
                            size_t *nmiss);

Read a horizontal slice of a variable (4.1.17)

streamReadVarSliceF

    void streamReadVarSliceF(int streamID, int varID, int levelID, float *data,
                             size_t *nmiss);

Read a horizontal slice of a variable (4.1.18)

streamWriteVar

    void streamWriteVar(int streamID, int varID, const double *data, size_t nmiss);

Write a variable (4.1.11)

streamWriteVarF

    void streamWriteVarF(int streamID, int varID, const float *data, size_t nmiss);

Write a variable (4.1.12)

streamWriteVarSlice

    void streamWriteVarSlice(int streamID, int varID, int levelID, const double *data,
                             size_t nmiss);

Write a horizontal slice of a variable (4.1.13)

streamWriteVarSliceF

    void streamWriteVarSliceF(int streamID, int varID, int levelID, const float *data,
                              size_t nmiss);

Write a horizontal slice of a variable (4.1.14)

taxisCreate

    int taxisCreate(int taxistype);

Create a Time axis (4.8.1)

taxisDefCalendar

    void taxisDefCalendar(int taxisID, int calendar);

Define the calendar (4.8.11)

taxisDefRdate

    void taxisDefRdate(int taxisID, int64_t rdate);

Define the reference date (4.8.3)

taxisDefRtime

    void taxisDefRtime(int taxisID, int rtime);

Define the reference time (4.8.5)

taxisDefVdate

    void taxisDefVdate(int taxisID, int64_t vdate);

Define the verification date (4.8.7)

taxisDefVtime

    void taxisDefVtime(int taxisID, int vtime);

Define the verification time (4.8.9)

taxisDestroy

    void taxisDestroy(int taxisID);

Destroy a Time axis (4.8.2)

taxisInqCalendar

    int taxisInqCalendar(int taxisID);

Get the calendar (4.8.12)

taxisInqRdate

    int64_t taxisInqRdate(int taxisID);

Get the reference date (4.8.4)

taxisInqRtime

    int taxisInqRtime(int taxisID);

Get the reference time (4.8.6)

taxisInqVdate

    int64_t taxisInqVdate(int taxisID);

Get the verification date (4.8.8)

taxisInqVtime

    int taxisInqVtime(int taxisID);

Get the verification time (4.8.10)

vlistCat

    void vlistCat(int vlistID2, int vlistID1);

Concatenate two variable lists (4.2.5)

vlistCopy

    void vlistCopy(int vlistID2, int vlistID1);

Copy a variable list (4.2.3)

vlistCopyFlag

    void vlistCopyFlag(int vlistID2, int vlistID1);

Copy some entries of a variable list (4.2.6)

vlistCreate

    int vlistCreate(void);

Create a variable list (4.2.1)

vlistDefTaxis

    void vlistDefTaxis(int vlistID, int taxisID);

Define the time axis (4.2.10)

vlistDefVar

    int vlistDefVar(int vlistID, int gridID, int zaxisID, int timetype);

Define a Variable (4.3.1)

vlistDefVarCode

    void vlistDefVarCode(int vlistID, int varID, int code);

Define the code number of a Variable (4.3.5)

vlistDefVarDatatype

    void vlistDefVarDatatype(int vlistID, int varID, int datatype);

Define the data type of a Variable (4.3.7)

vlistDefVarMissval

    void vlistDefVarMissval(int vlistID, int varID, double missval);

Define the missing value of a Variable (4.3.9)

vlistDestroy

    void vlistDestroy(int vlistID);

Destroy a variable list (4.2.2)

vlistDuplicate

    int vlistDuplicate(int vlistID);

Duplicate a variable list (4.2.4)

vlistInqTaxis

    int vlistInqTaxis(int vlistID);

Get the time axis (4.2.11)

vlistInqVarCode

    int vlistInqVarCode(int vlistID, int varID);

Get the Code number of a Variable (4.3.6)

vlistInqVarDatatype

    int vlistInqVarDatatype(int vlistID, int varID);

Get the data type of a Variable (4.3.8)

vlistInqVarGrid

    int vlistInqVarGrid(int vlistID, int varID);

Get the Grid ID of a Variable (4.3.2)

vlistInqVarMissval

    double vlistInqVarMissval(int vlistID, int varID);

Get the missing value of a Variable (4.3.10)

vlistInqVarTsteptype

    int vlistInqVarTsteptype(int vlistID, int varID);

Get the timestep type of a Variable (4.3.4)

vlistInqVarZaxis

    int vlistInqVarZaxis(int vlistID, int varID);

Get the Zaxis ID of a Variable (4.3.3)

vlistNgrids

    int vlistNgrids(int vlistID);

Number of grids in a variable list (4.2.8)

vlistNvars

    int vlistNvars(int vlistID);

Number of variables in a variable list (4.2.7)

vlistNzaxis

    int vlistNzaxis(int vlistID);

Number of zaxis in a variable list (4.2.9)

zaxisCreate

    int zaxisCreate(int zaxistype, int size);

Create a vertical Z-axis (4.7.1)

zaxisDefLevels

    void zaxisDefLevels(int zaxisID, const double *levels);

Define the levels of a Z-axis (4.7.5)

zaxisDestroy

    void zaxisDestroy(int zaxisID);

Destroy a vertical Z-axis (4.7.2)

zaxisInqLevel

    double zaxisInqLevel(int zaxisID, int levelID);

Get one level of a Z-axis (4.7.7)

zaxisInqLevels

    void zaxisInqLevels(int zaxisID, double *levels);

Get all levels of a Z-axis (4.7.6)

zaxisInqSize

    int zaxisInqSize(int zaxisID);

Get the size of a Z-axis (4.7.4)

zaxisInqType

    int zaxisInqType(int zaxisID);

Get the type of a Z-axis (4.7.3)

B.  Examples

This appendix contains complete examples to write, read and copy a dataset with the CDI library.

B.1  Write a dataset

Here is an example using CDI to write a NetCDF dataset with 2 variables on 3 time steps. The first variable is a 2D field on surface level and the second variable is a 3D field on 5 pressure levels. Both variables are on the same lon/lat grid.

B.1.1  Result

This is the ncdump -h output of the resulting NetCDF file example.nc.

B.2  Read a dataset

This example reads the NetCDF file example.nc from Appendix B.1.

B.3  Copy a dataset

This example reads the NetCDF file example.nc from Appendix B.1 and writes the result to a GRIB dataset by simple setting the output file type to CDI_FILETYPE_GRB.

C.  Environment Variables

The following table describes the environment variables that affect CDI.

Function index