Input files as binary masks
Added by Martin Großhauser about 14 years ago
Hello,
first thanks for cdo, it's a great tool!
I'm trying to do some calculations with binary masks, but I have no idea how to do it with cdo. Here's what I want to do:
- I have an input file #1 with 3 or 4 dimensions: timestep, (level, ) latitude, longitude
- and I have another input file 2 with just the timestep dimension and a mask field with "1" and "0" (or missing) values
- I want to make calculations (e. g. mean, std) in #1 including only the timesteps where the mask field from #2 is set to "1"
Is that possibly with cdo?
Best regards,
Martin
Replies (4)
RE: Input files as binary masks - Added by Uwe Schulzweida about 14 years ago
Hello Martin,
Unfortunately this functionality is not implemented, sorry.
Best regards,
Uwe
RE: Input files as binary masks - Added by Uwe Schulzweida almost 14 years ago
Submitted by mail from Lawson Hanson:
Hello,
Have you tried using the "ifthen" operator?
I think this will do what you want?
RE: Input files as binary masks - Added by Uwe Schulzweida almost 14 years ago
Yes, in this case the mask file needs to have the same grid size as the input file. This can be achieved with the operator enlarge:
cdo <calculation> -ifthen -enlarge,ifile maskfile ifile ofileBut I have never tried it with a netCDF maskfile which has only the timestep dimension.
Best regards,
Uwe
RE: Input files as binary masks - Added by Martin Großhauser almost 14 years ago
Running cdo with "ifthen" like suggested above runs without an error, but ofile is identical to ifile. As maskfile I used an enlarged netcdf-file (also tried with grib), enlarging seems to work correctly: the whole lat-lon grid for each timestep is either zero or one, correctly computed from the 1D (time) mask. Creating the mask with missing/fill values instead of zeros doesn't work; enlarge accept missing values. I will attach NCL dumps of the input files. (I also tried with both inputs as netcdf).
ifile:
Variable: b (file variable)
filename: CompEra40AllSfc
path: CompEra40AllSfc.grib
file global attributes:
dimensions:
initial_time0_hours = 528
g0_lat_1 = 32
g0_lon_2 = 33
variables:
float CI_GDS0_SFC_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
center : European Center for Medium-Range Weather Forecasts (RSMC)
long_name : Sea-ice cover
units : (0 - 1)
_FillValue : 1e+20
level_indicator : 1
gds_grid_type : 0
parameter_table_version : 128
parameter_number : 31
forecast_time : 0
forecast_time_units : hours
float SSTK_GDS0_SFC_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
center : European Center for Medium-Range Weather Forecasts (RSMC)
long_name : Sea surface temperature
units : K
_FillValue : 1e+20
level_indicator : 1
gds_grid_type : 0
parameter_table_version : 128
parameter_number : 34
forecast_time : 0
forecast_time_units : hours
float SWVL1_GDS0_DBLY_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
center : European Center for Medium-Range Weather Forecasts (RSMC)
long_name : Volumetric soil water layer 1
units : m**3 m**-3
_FillValue : 1e+20
level_indicator : 112
gds_grid_type : 0
parameter_table_version : 128
parameter_number : 39
level : ( 0, 7 )
forecast_time : 0
forecast_time_units : hours
float SWVL2_GDS0_DBLY_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
center : European Center for Medium-Range Weather Forecasts (RSMC)
long_name : Volumetric soil water layer 2
units : m**3 m**-3
_FillValue : 1e+20
level_indicator : 112
gds_grid_type : 0
parameter_table_version : 128
parameter_number : 40
level : ( 7, 28 )
forecast_time : 0
forecast_time_units : hours
[... some more variables ...]
float STL4_GDS0_DBLY_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
center : European Center for Medium-Range Weather Forecasts (RSMC)
long_name : Soil temperature level 4
units : K
_FillValue : 1e+20
level_indicator : 112
gds_grid_type : 0
parameter_table_version : 128
parameter_number : 236
level : ( 100, 255 )
forecast_time : 0
forecast_time_units : hours
double initial_time0_hours ( initial_time0_hours )
long_name : initial time
units : hours since 1800-01-01 00:00
double initial_time0_encoded ( initial_time0_hours )
long_name : initial time encoded as double
units : yyyymmddhh.hh_frac
float g0_lat_1 ( g0_lat_1 )
long_name : latitude
GridType : Cylindrical Equidistant Projection Grid
units : degrees_north
Dj : 1.125
Di : 1.125
Lo2 : 298.125
La2 : -27
Lo1 : 262.125
La1 : 7.875
float g0_lon_2 ( g0_lon_2 )
long_name : longitude
GridType : Cylindrical Equidistant Projection Grid
units : degrees_east
Dj : 1.125
Di : 1.125
Lo2 : 298.125
La2 : -27
Lo1 : 262.125
La1 : 7.875
string initial_time0 ( initial_time0_hours )
long_name : Initial time of first record
units : mm/dd/yyyy (hh:mm)
maskfile:
Variable: a (file variable)
filename: enlarged
path: enlarged.grib
file global attributes:
dimensions:
initial_time0_hours = 528
g0_lat_1 = 32
g0_lon_2 = 33
variables:
float PRES_GDS0_SFC_10 ( initial_time0_hours, g0_lat_1, g0_lon_2 )
long_name : Pressure
units : Pa
_FillValue : 1e+20
level_indicator : 1
gds_grid_type : 0
parameter_table_version : 0
parameter_number : 1
forecast_time : 0
forecast_time_units : hours
double initial_time0_hours ( initial_time0_hours )
long_name : initial time
units : hours since 1800-01-01 00:00
double initial_time0_encoded ( initial_time0_hours )
long_name : initial time encoded as double
units : yyyymmddhh.hh_frac
float g0_lat_1 ( g0_lat_1 )
long_name : latitude
GridType : Cylindrical Equidistant Projection Grid
units : degrees_north
Dj : 1.125
Di : 1.125
Lo2 : 298.125
La2 : -27
Lo1 : 262.125
La1 : 7.875
float g0_lon_2 ( g0_lon_2 )
long_name : longitude
GridType : Cylindrical Equidistant Projection Grid
units : degrees_east
Dj : 1.125
Di : 1.125
Lo2 : 298.125
La2 : -27
Lo1 : 262.125
La1 : 7.875
string initial_time0 ( initial_time0_hours )
long_name : Initial time of first record
units : mm/dd/yyyy (hh:mm)