def upgrade_bufr_file(input_bufr_file, output_bufr_file):
# #[
"""
an example routine to demonstrate how to read a BUFR message,
upgrade it's edition number, and write it to an output BUFR file
"""
# get 2 instances of the RawBUFRFile class
rbf_in = RawBUFRFile()
rbf_out = RawBUFRFile()
# open the file for reading, count nr of BUFR messages in it
# and store its content in memory, together with
# an array of pointers to the start and end of each BUFR message
rbf_in.open(input_bufr_file, 'rb')
# open the file for writing
rbf_out.open(output_bufr_file, 'wb')
# extract the number of BUFR messages from the file
num_msgs = rbf_in.get_num_bufr_msgs()
for msg_nr in range(1, num_msgs+1):
raw_msg, section_sizes, section_start_locations = \
rbf_in.get_raw_bufr_msg(msg_nr)
bufr_obj = BUFRInterfaceECMWF(raw_msg, section_sizes,
section_start_locations,
verbose=True)
bufr_obj.decode_sections_012()
bufr_obj.setup_tables()
bufr_obj.decode_data()
nsub = bufr_obj.get_num_subsets()
n_exp_descr = len(bufr_obj.values)/nsub
bufr_obj.fill_descriptor_list(nr_of_expanded_descriptors=n_exp_descr)
bufr_obj.ksec0[3-1] = 4 # set bufr edition to 4
bufr_obj.ktdlst = bufr_obj.get_descriptor_list()
# extract delayed replication factors
delayed_repl_data = bufr_obj.derive_delayed_repl_factors()
# fill the list of replication factors
bufr_obj.fill_delayed_repl_data(delayed_repl_data)
# activate this one if the encoding crashes without clear cause:
# bufr_obj.estimated_num_bytes_for_encoding = 25000
# encode the data
bufr_obj.encode_data(bufr_obj.values, bufr_obj.cvals)
print 'Encode BUFR msg %i' % msg_nr
rbf_out.write_raw_bufr_msg(bufr_obj.encoded_message)
# close the file
rbf_in.close()
rbf_out.close()
