CDO

hi Rachel!

Please have a look into the select operator It accepts multiple input files and use the same selection on all of them.

example call:

cdo -select,date=2003-12-03T14:30:00 <input files> <output file> 

cheers
ralf

Hi Ralf,

Thanks very much for your reply and help. I think I may not have explained my problem very clearly though. I am not trying to make the same selection on multiple input files, but to take the time axis from one file, and use that to select identical times from the second file. Is that possible, do you know?

Thanks again!
-Rachel

Hi Rachel,

I think I have an idea that what you want. It should be something like this, but I am having an error saying "No such file or directory". I am not sure how to fix that part, maybe Ralph can help with that.

VARIABLE=$(cdo showtimestamp firstfile.nc)
cdo -select,date=$VARIABLE secondfile.nc output.nc

Kind regards,

Estanislao

Hi Estanislao,

That sounds genius! I played around with it a bit, and unfortunately I think there is something wrong with the formatting with passing the timestamp directly to -select,date because when it says "No such file or directory", it assumes that the date is the input file as there is a space before it where there should be (I think) a comma. That's alright, I think I've figured out a different approach to the problem which should work. Thanks both anyway for your help - hugely appreciated!

Many thanks,
-Rachel

Hi Rachel,

as you well guessed there should be a comma after each date. If you find a way around please post it. Other people will benefit from your script.

Kind regards,

Estanislao

replace space with comma:

Lets start with a list of timesteps:

% cdo -O -f nc -s -showtimestamp -settaxis,2001-01-01,12:00:00,12hours -for,1,10
  2001-01-01T12:00:00  2001-01-02T00:00:00  2001-01-02T12:00:00  2001-01-03T00:00:00  2001-01-03T12:00:00  2001-01-04T00:00:00  2001-01-04T12:00:00  2001-01-05T00:00:00  2001-01-05T12:00:00  2001-01-06T00:00:00

this can be piped through sed or perl to do text replacement. I will use sed to remove the leading spaces and perl to replace the two spaces between timestamps with a single comma:

% cdo -s -showtimestamp -settaxis,2001-01-01,12:00:00,12hours -for,1,10 | sed 's/^[ \t]*//' | perl -pe 's/  /,/g' 
2001-01-01T12:00:00,2001-01-02T00:00:00,2001-01-02T12:00:00,2001-01-03T00:00:00,2001-01-03T12:00:00,2001-01-04T00:00:00,2001-01-04T12:00:00,2001-01-05T00:00:00,2001-01-05T12:00:00,2001-01-06T00:00:00

So with a variable like

TIMESTEPS=$(cdo -s -showtimestamp -settaxis,2001-01-01,12:00:00,12hours -for,1,10 | sed 's/^[ \t]*//' | perl -pe 's/  /,/g')

in-fact you can call this in a single line without the variable if you want:

% cdo -s -showyear -select,date=$(cdo -s -showtimestamp -settaxis,2001-01-01,12:00:00,12hours -for,1,10 | sed 's/^[ \t]*//' | perl -pe 's/  /,/g' ) -settaxis,2001-01-01,12:00:00,12hours -for,1,10 
 2001

cheers
ralf

Wow, Ralf, that's incredible! Thanks for your help - amazing!

I am always learning something new thanks to Ralph. Rachel, bear in mind that 'for' is selecting the first 10 timesteps. You will have to change that

thx, Rachel. My goto docu for shell is the Advanced Bash Scripting Guide Although it's kind of old, it's still valid. Bash is kind of old, too.

If there were no leading spaces and only a single space between the timestamps, the call would be a lot simpler:

 cdo -s -showtimestamp inputfile.nc | tr ' ' ','

I am sure there is also a solution with sed, only. But I never got used to sed very much, that's why I use perl most of the time.

Estanislao Gavilan wrote in RE: Selecting same dates as another file:

I am always learning something new thanks to Ralph. Rachel, bear in mind that 'for' is selecting the first 10 timesteps. You will have to change that

ah, yes! I totally forgot to mention: this constuct -settaxis,2001-01-01,12:00:00,12hours -for,1,10 emulates a time series - you must replace it with your input files.

thx Estanislao

Thanks both! Yes, I worked out that I would need to replace the time axis with my own files. Also that the dates matched, but not the times, so if anyone else has a similar issue -showdate worked when I couldn't use -showtimestamp

Thanks again Ralf and Estanislao! Very informative!