Added Python example for grib_ls JSON output

examples/python/grib_ls_JSON.py

@@ -0,0 +1,106 @@
+# Copyright 2005-2016 ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
+# virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
+#
+# Python implementation:  bufr_read_tropical_cyclone
+#
+# Description: how to read data of the ECMWF EPS tropical cyclone tracks encoded in BUFR format.
+#
+
+import traceback
+import sys
+import os
+import getopt
+from eccodes import *
+
+VERBOSE=1 # verbose error reporting
+default_namespace='ls'
+
+def do_print(namespace, INPUT):
+    f = open(INPUT)
+    first_time = True
+
+    print '{'
+    print '   "messages" : ['
+    while 1:
+        gid = codes_grib_new_from_file(f)
+        if gid is None:
+            break
+
+        if not first_time:
+            print '      ,{'
+        else:
+            print '      {'
+            first_time = False
+
+        iterid = codes_keys_iterator_new(gid, namespace)
+
+        f1 = True
+        while codes_keys_iterator_next(iterid):
+            keyname = codes_keys_iterator_get_name(iterid)
+            keyval = codes_get_string(iterid,keyname)
+            if not f1:
+                print ','
+            else:
+                print ''
+                f1 = False
+            print "         \"%s\" : \"%s\"" % (keyname,keyval),
+
+        print ''
+        print '      }'
+        codes_keys_iterator_delete(iterid)
+        codes_release(gid)
+
+    print '   ]'
+    print '}'
+    f.close()
+
+def usage():
+    progname = os.path.basename(sys.argv[0])
+    print "Usage: ", progname, "[options] grib_file1 grib_file2 ..."
+    print 'Options:'
+    print '\t-n namespace'
+    print '\t\tAll the keys belonging to namespace are printed.'
+    print '\t-m Mars keys are printed.'
+    print ''
+
+def main():
+    if len(sys.argv) < 2:
+        usage()
+        return 1
+    try:
+        options = "mn:"
+        namespace = default_namespace
+        opts, args = getopt.getopt(sys.argv[1:], options)
+        for o, a in opts:
+            if o == '-m':
+                namespace = 'mars'
+            elif o == '-n':
+                namespace = a or default_namespace
+            else:
+                assert False, 'Invalid option'
+
+        # Check we have some GRIB files to process
+        if not args:
+            usage()
+            return 1
+        for arg in args:
+            do_print(namespace, arg)
+    except getopt.GetoptError as err:
+        print 'Error: ',err
+        usage()
+        return 1
+    except GribInternalError as err:
+        if VERBOSE:
+            traceback.print_exc(file=sys.stderr)
+        else:
+            print >>sys.stderr,err.msg
+
+        return 1
+
+if __name__ == "__main__":
+    sys.exit(main())