Allow to use the --filter option multiple times

Replace the 'store' action with 'append', so that the --filter option
can be used multiple times: every time that optparse encounters the
option, the photometric filter is appended to the destination. This
makes it possible to specify not only one, but multiple filters on
which photometry will be done — while the rest are ignored.

This merges branch 'multiple-filter-options'

photometry.py

@@ -226,11 +226,13 @@ def parallel_photometry(args):
 parser.add_option('--overwrite', action = 'store_true', dest = 'overwrite',
                   help = "overwrite output database if it already exists")
 
-parser.add_option('--filter', action = 'store', type = 'passband',
-                  dest = 'filter', default = None,
+parser.add_option('--filter', action = 'append', type = 'passband',
+                  dest = 'filters', default = None,
                   help = "do not do photometry on all the FITS files given "
                   "as input, but only on those taken in this photometric "
-                  "filter. " + defaults.desc['filter'])
+                  "filter. This option may be used multiple times in order "
+                  "to specify more than one filter with which we want to "
+                  "work. " + defaults.desc['filter'])
 
 parser.add_option('--maximum', action = 'store', type = 'int',
                   dest = 'maximum', default = defaults.maximum,
@@ -744,34 +746,42 @@ def get_date(img):
 
     # The --filter option allows the user to specify on which FITS files, among
     # all those received as input, photometry must be done: only those files in
-    # the options.filter photometric filter. The Passband class, which supports
-    # comparison operations, makes it possible to compare filters for what they
-    # really are, not how they were written: "Johnson V" and "johnson_v", for
-    # example, are the same filter after all, but if we just compared the two
-    # strings we would consider them to be different.
-    if options.filter:
-
-        msg = "%sIgnoring images not taken in the '%s' photometric filter..."
-        print msg % (style.prefix, options.filter) ,
+    # any of the photometric filters contained in options.filter. The Passband
+    # class, which supports comparison operations, makes it possible to compare
+    # filters for what they really are, not how they were written: "Johnson V"
+    # and "johnson_v", for example, are the same filter after all, but if we
+    # just compared the two strings we would consider them to be different.
+
+    if options.filters:
+
+        msg = "%sIgnoring images not taken in any of the following filters:"
+        print msg % style.prefix
+        for index, pfilter in enumerate(sorted(options.filters)):
+            print "%s (%d) %s" % (style.prefix, index + 1, pfilter)
         sys.stdout.flush()
 
         discarded = 0
         for pfilter, images in files.items():
-            if pfilter != options.filter:
+            if pfilter not in options.filters:
                 discarded += len(images)
                 del files[pfilter]
 
         if not files:
             print
-            msg = "%sError. No image was taken in the '%s' filter."
-            print msg % (style.prefix, options.filter)
+            msg = "%sError. No image was taken in any of the above filters."
+            print msg % style.prefix
             print style.error_exit_message
             return 1
 
         else:
-            print 'done.'
-            msg = "%s%d images taken in the '%s' filter, %d were discarded."
-            print msg % (style.prefix, len(files), options.filter, discarded)
+            former_total = len(files) + discarded
+            msg = "%s%d images (%.2f %%) taken in the above filters,"
+            percentage = len(files) / former_total * 100
+            print msg % (style.prefix, len(files), percentage) ,
+
+            msg = "%d (%.2f %%) were discarded."
+            percentage = discarded / former_total * 100
+            print msg % (discarded, percentage)
 
     # If a JSON file is specified with --annuli, it must list the photometric
     # parameters for all the filters on which photometry is to be done.