mirror of https://github.com/ecmwf/eccodes.git
108 lines
3.1 KiB
Python
108 lines
3.1 KiB
Python
# (C) Copyright 2005- ECMWF.
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#
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# This software is licensed under the terms of the Apache Licence Version 2.0
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# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
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#
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# In applying this licence, ECMWF does not waive the privileges and immunities
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# granted to it by virtue of its status as an intergovernmental organisation
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# nor does it submit to any jurisdiction.
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#
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# Python implementation: bufr_read_scatterometer
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#
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# Description: How to read data for a given beam from scatterometer BUFR
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# messages.
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#
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# Please note that scatterometer data can be encoded in various ways in BUFR.
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# Therefore the code below might not work directly for other types of messages
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# than the one used in the example. It is advised to use bufr_dump first to
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# understand the structure of these messages.
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#
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import sys
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import traceback
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from eccodes import *
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INPUT = "../../data/bufr/asca_139.bufr"
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VERBOSE = 1 # verbose error reporting
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def example():
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# open bufr file
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f = open(INPUT, "rb")
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cnt = 0
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# loop for the messages in the file
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while 1:
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# get handle for message
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bufr = codes_bufr_new_from_file(f)
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if bufr is None:
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break
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print("message: %s" % cnt)
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# We need to instruct ecCodes to expand all the descriptors
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# i.e. unpack the data values
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codes_set(bufr, "unpack", 1)
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# The BUFR file contains a single message with 2016 subsets in a
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# compressed form. It means each subset has exactly the same structure:
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# they store one location with several beams and one backscatter value
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# in each beam.
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#
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# To print the backScatter values for beamIdentifier=2 from all the
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# subsets we will simply access the key by condition (see below)
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# Get the total number of subsets.
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numObs = codes_get(bufr, "numberOfSubsets")
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print(" Number of values: %ld" % numObs)
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# Get latitude (for all the subsets)
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lat = codes_get_array(bufr, "latitude")
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# Get longitude (for all the subsets)
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lon = codes_get_array(bufr, "longitude")
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# Get backScatter for beam two. We use an access by condition for this
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# key (for all the subsets).
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bscat = codes_get_array(bufr, "/beamIdentifier=2/backscatter")
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# Check that all arrays are same size
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if len(lat) != numObs or len(lon) != numObs or len(bscat) != numObs:
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print("inconsistent array dimension")
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return 1
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# Print the values
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print("pixel lat lon backscatter")
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print("-------------------------------")
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for i in range(numObs):
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print("%3d %.2f %.2f %.2f" % (i + 1, lat[i], lon[i], bscat[i]))
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cnt += 1
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# Release handle
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codes_release(bufr)
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# Close the file
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f.close()
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def main():
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try:
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example()
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except CodesInternalError as err:
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if VERBOSE:
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traceback.print_exc(file=sys.stderr)
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else:
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sys.stderr.write(err.msg + "\n")
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return 1
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if __name__ == "__main__":
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sys.exit(main())
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