FAQ — Frequently Asked Questions

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• ecCodes does not seem to be found by Python

  => (re-)install eccodes support for Python : pip3 install --user eccodes

  if that is not enough, reinstall epygram:

  • clean any reference to epygram in your environment

  • unset PYTHONPATH

  • @ CNRM, reinstall epygram running $EPYGRAM_INSTALL_DIR/_install/install_epygram.py -e

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• I have rather esoterical errors when I try to read a FA file…

  => the epygram.init_env() may be initialized at the beginning of your script(s), to be sure the arpifs4py library do not use MPI, or uses OpenMP with an initialized environment.

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• There is a field in my Surfex FA file, recognized as MiscField by epygram whereas it is H2D, or vice-versa; how can I manage to read it ?

  => edit $HOME/.epygram/sfxflddesc_mod.F90, and add your field in the manner of the examples given therein or in $EPYGRAM_INSTALL_DIR/epygram/data/sfxflddesc_mod.F90. And warn the epygram team about it, so that it will enter next version default sfxflddesc_mod.F90.

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• I need to overwrite the faFieldName.def ecCodes definition file for FA fieldnames conversion to GRIB2 parameters:

  => copy $HOME/.epygram/gribapi.def.0/ as $HOME/.epygram/gribapi.def.99/, then edit $HOME/.epygram/gribapi.def.99/grib2/localConcepts/lfpw/faFieldName.def and set any field therein.

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• My PC does not have enough memory to deal with these global spectral fields…

  >>> Legendre spectral transforms need XX.XX MB
  >>> memory, while only YY.YY MB is available:
  >>> SWAPPING prevented !
  

  => either:

  • run your script on supercomputers using the alias s1batch='sbatch -N 1 -p normal256 --mem 250000 -t 00:30:00' e.g.: s1batch myscript.py options -of -my --script

  • use the fa_sp2gp.py tool on Bull (using the above alias) to convert your file to all-gridpoint then work in gridpoint space

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• I have a brutal crash (e.g. SegFault) while working with some large size fields…

  => before running Python, you need to raise the stack size limit: ulimit -s unlimited

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• How to hide LFI/FA messages ?

  => either:

  • export FA4PY_MUTE=1

  • edit $HOME/.epygram/userconfig.py and set FA_mute_FA4py = True

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• How to modify values of parameters or options of ``epygram`` *configuration* ?

  => values of epygram.config can be modified in $HOME/.epygram/userconfig.py

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(to be continued…)