source: flex_extract.git/Source/Python/Classes/GribUtil.py @ c77630a

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#*******************************************************************************
# @Author: Anne Fouilloux (University of Oslo)
#
# @Date: July 2014
#
# @Change History:
#   February 2018 - Anne Philipp (University of Vienna):
#        - applied PEP8 style guide
#        - added documentation
#        - changed some naming
#
# @License:
#    (C) Copyright 2014-2019.
#    Anne Philipp, Leopold Haimberger
#
#    SPDX-License-Identifier: CC-BY-4.0
#
#    This work is licensed under the Creative Commons Attribution 4.0
#    International License. To view a copy of this license, visit
#    http://creativecommons.org/licenses/by/4.0/ or send a letter to
#    Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
#*******************************************************************************

# ------------------------------------------------------------------------------
# MODULES
# ------------------------------------------------------------------------------
from __future__ import print_function

import os

# ------------------------------------------------------------------------------
# CLASS
# ------------------------------------------------------------------------------
class GribUtil(object):
    '''
    Class for GRIB utilities (new methods) based on GRIB API

    The GRIB API provides all necessary tools to work directly with the
    grib files. Nevertheless, the GRIB API tools are very basic and are in
    direct connection with the grib files. This class provides some higher
    functions which apply a set of GRIB API tools together in the respective
    context. So, the class initially contains a list of grib files (their
    names) and the using program then applies the methods directly on the
    class objects without having to think about how the actual GRIB API
    tools have to be arranged.
    '''
    # --------------------------------------------------------------------------
    # CLASS FUNCTIONS
    # --------------------------------------------------------------------------
    def __init__(self, filenames):
        '''Initialise an object of GribUtil and assign a list of filenames.

        Parameters
        ----------
        filenames : :obj:`list` of :obj:`strings`
             A list of filenames.

        Return
        ------

        '''

        self.filenames = filenames

        return


    def get_keys(self, keynames, wherekeynames=[], wherekeyvalues=[]):
        '''Get keyvalues for a given list of keynames a where statement
        can be given (list of key and list of values)

        Parameters
        ----------
        keynames : :obj:`list` of :obj:`string`
            List of keynames.

        wherekeynames : :obj:`list` of :obj:`string`, optional
            Default value is an empty list.

        wherekeyvalues : :obj:`list` of :obj:`string`, optional
            Default value is an empty list.

        Return
        ------
        return_list : :obj:`list` of :obj:`string`
            List of keyvalues for given keynames.
        '''
        from eccodes import (codes_new_from_file, codes_is_defined, codes_get,
                             codes_release)

        return_list = []

        with open(self.filenames, 'rb') as fileid:

            gid = codes_new_from_file(fileid)

            if len(wherekeynames) != len(wherekeyvalues):
                raise Exception("Number of key values and key names must be \
                                 the same. Give a value for each keyname!")

            select = True
            i = 0
            for wherekey in wherekeynames:
                if not codes_is_defined(gid, wherekey):
                    raise Exception("where key was not defined")

                select = (select and (str(wherekeyvalues[i]) ==
                                      str(codes_get(gid, wherekey))))
                i += 1

            if select:
                llist = []
                for key in keynames:
                    llist.extend([str(codes_get(gid, key))])
                return_list.append(llist)

            codes_release(gid)

        return return_list


    def set_keys(self, fromfile, keynames, keyvalues, wherekeynames=[],
                 wherekeyvalues=[], strict=False, filemode='wb'):
        '''Opens the file to read the grib messages and then write
        the selected messages (with wherekeys) to a new output file.
        Also, the keyvalues of the passed list of keynames are set.

        Parameters
        ----------
        fromfile : :obj:`string`
            Filename of the input file to read the grib messages from.

        keynames : :obj:`list` of :obj:`string`
            List of keynames to set in the selected messages.
            Default is an empty list.

        keyvalues : :obj:`list` of :obj:`string`
            List of keyvalues to set in the selected messages.
            Default is an empty list.

        wherekeynames : :obj:`list` of :obj:`string`, optional
            List of keynames to select correct message.
            Default value is an empty list.

        wherekeyvalues : :obj:`list` of :obj:`string`, optional
            List of keyvalues for keynames to select correct message.
            Default value is an empty list.

        strict : :obj:`boolean`, optional
            Decides if everything from keynames and keyvalues
            is written out the grib file (False) or only those
            meeting the where statement (True). Default is False.

        filemode : :obj:`string`, optional
            Sets the mode for the output file. Default is "wb".

        Return
        ------

        '''
        from eccodes import (codes_grib_new_from_file, codes_is_defined,
                             codes_get, codes_set, codes_write,
                             codes_set_values, codes_release)

        if len(wherekeynames) != len(wherekeyvalues):
            raise Exception("Give a value for each keyname!")

        fout = open(self.filenames, filemode)

        with open(fromfile, 'rb') as fin:
            gid = codes_grib_new_from_file(fin)

            select = True
            i = 0
            for wherekey in wherekeynames:
                if not codes_is_defined(gid, wherekey):
                    raise Exception("wherekey was not defined")

                select = (select and (str(wherekeyvalues[i]) ==
                                      str(codes_get(gid, wherekey))))
                i += 1

            if select:
                i = 0
                for key in keynames:
                    if key == 'values':
                        codes_set_values(gid, keyvalues[i])
                    else:
                        codes_set(gid, key, keyvalues[i])
                    i += 1

                codes_write(gid, fout)

            codes_release(gid)

        fout.close()

        return

    def copy_dummy_msg(self, filename_in, selectWhere=True,
                 keynames=[], keyvalues=[], filemode='wb'):
        '''Add the content of another input grib file to the objects file but
        only messages corresponding to keys/values passed to the function.
        The selectWhere switch decides if to copy the keys equal to (True) or
        different to (False) the keynames/keyvalues list passed to the function.

        Parameters
        ----------
        filename_in : :obj:`string`
            Filename of the input file to read the grib messages from.

        selectWhere : :obj:`boolean`, optional
            Decides if to copy the keynames and values equal to (True) or
            different to (False) the keynames/keyvalues list passed to the
            function. Default is True.

        keynames : :obj:`list` of :obj:`string`, optional
            List of keynames. Default is an empty list.

        keyvalues : :obj:`list` of :obj:`string`, optional
            List of keyvalues. Default is an empty list.

        filemode : :obj:`string`, optional
            Sets the mode for the output file. Default is "wb".

        Return
        ------

        '''
        from eccodes import (codes_grib_new_from_file, codes_is_defined,
                             codes_get, codes_release, codes_write)

        if len(keynames) != len(keyvalues):
            raise Exception("Give a value for each keyname!")


        fout = open(self.filenames, filemode)

        fields = 0

        with open(filename_in, 'rb') as fin:
            if fields >= 1:
                fout.close()
                return

            gid = codes_grib_new_from_file(fin)

            select = True
            i = 0
            for key in keynames:
                if not codes_is_defined(gid, key):
                    raise Exception("Key was not defined")

                if selectWhere:
                    select = (select and (str(keyvalues[i]) ==
                                          str(codes_get(gid, key))))
                else:
                    select = (select and (str(keyvalues[i]) !=
                                          str(codes_get(gid, key))))
                i += 1

            if select:
                fields = fields + 1
                codes_write(gid, fout)

            codes_release(gid)

        fout.close()

        return

    def index(self, index_keys=["mars"], index_file="my.idx"):
        '''Create index file from a list of files if it does not exist or
        read an index file.

        Parameters
        ----------
        index_keys: :obj:`list` of :obj:`string`, optional
            Contains the list of key parameter names from
            which the index is to be created.
            Default is a list with a single entry string "mars".

        index_file: :obj:`string`, optional
            Filename where the indices are stored.
            Default is "my.idx".

        Return
        ------
        iid: :obj:`integer`
            Grib index id.
        '''
        from eccodes import (codes_index_read, codes_index_new_from_file,
                             codes_index_add_file, codes_index_write)

        print("... index will be done")
        iid = None

        if os.path.exists(index_file):
            iid = codes_index_read(index_file)
            print("Use existing index file: %s " % (index_file))
        else:
            for filename in self.filenames:
                print("Inputfile: %s " % (filename))
                if iid is None:
                    iid = codes_index_new_from_file(filename, index_keys)
                else:
                    codes_index_add_file(iid, filename)

            if iid is not None:
                codes_index_write(iid, index_file)

        print('... index done')

        return iid