FAQ

The Library

1. 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.

2. There is a field in my FA file, unknown by epygram (or it seems to be recognized as a MiscField); how can I manage to read it ?

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

3. I have built a new format class FMFILE (or whatever else) for epygram, and I want it to be “fully” integrated in the package locally on my platform (so that the epygram.formats.resource() can return it). How can I do ?

   => edit $HOME/.epygram/userconfig.py, and:

   • add

     >>> usermodules = [{'name':'FMFILE', 'abspath':'/path/to/FMFILE.py'}]
     

   • copy the variable epygram.config.implemented_formats in it, adding FMFILE

4. How do epygram and vortex interconnect ?

   => Well ! Here is an example (having vortex installed), that fetches a resource on the archive and returns an epygram resource:

   >>> import epygram
   >>> epygram.init_env()
   >>> import usevortex
   >>> r = usevortex.get_resource(getmode='epygram',   # for the function to return the resource as an epygram object
                                  experiment='864G',                # XPID
                                  block='forecast',                 # Olive 'forecast' block (directory in archive)
                                  kind='gridpoint',                 # post-processed fields
                                  nativefmt='grib',                 # GRIBbed files
                                  date='2015041500',                # initial date and time
                                  term=3,                           # forecast term
                                  geometry='frangp0025',            # BDAP domain
                                  local='fcst_[term].[nativefmt]')  # local filename, once fetched
   

   Other resource descriptors are available, cf. usevortex.get_resource() documentation.

   vortex also is able to use epygram in order to handle a file’s content, cf. Vortex doc.

5. I want to add new features or methods to a class, epygram.fields.H2DField for instance, and be sure that my modifications will not be overwritten at the next upgrade of epygram...

   => build your class myH2DField in /path/to/myH2DField.py, making it inherit from epygram.fields.H2DField, as follows:

   #!/usr/bin/env python
   # -*- coding: utf-8 -*-
   import copy
   import footprints
   footprints.priorities.set_after('default','user')
   from epygram.fields import H2DField
   
   class myH2DField(H2DField):
       _footprint = dict(
           priority = dict(
               level = footprints.priorities.top.level('user')
           )
       )
   

   For this class to be used by epygram, you simply have to add it in $HOME/.epygram/userconfig.py:

   >>> usermodules = [{'name':'myH2DField', 'abspath':'/path/to/myH2DField.py'}]
   

   Anyway, if your modifications may be useful to others, propose to the epygram team its integration in the next version !

6. I want to add a personal colormap to be used by epygram.

   => write your colormap as RGB as below

   r1,g1,b1;
   r2,g2,b2;
   ...
   rn,gn,bn
   

   into file mycolormap.cmap. You may need the help of http://colormap.org

   Then in $HOME/.epygram/userconfig.py add:

   >>> usercolormaps = {'mycolormap', '/path/to/mycolormap.cmap'}
   

   and the colormap is now accesible to epygram.

(to be continued...)

Applicative tools

Option -h is your best friend !