QGIS » QGIS Application

In the latest versions of the Processing plugin (from 2.10 onwards), there are minor errors in the code. The following code should probably be used to replace the existing code:

##Table=group
##Input=vector
##Fields=Field Input
##Frequency=output table

from processing.tools.vector import TableWriter
from collections import defaultdict
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException

layer = processing.getObject(Input)    # Changed '(input)' to '(Input)'
inputFields = layer.pendingFields()
fieldIdxs = []
fields = Fields.split(',')    # Changed 'fields.split' to 'Fields.split'
for f in fields:
    idx = inputFields.indexFromName(f)
    if idx == -1:
        raise GeoAlgorithmExecutionException('Field not found:' + f)
    fieldIdxs.append(idx)
writer = TableWriter(Frequency, None, fields + ['FREQ'])    # Changed 'output' to 'Frequency'

counts = {}
feats = processing.features(layer)
nFeats = len(feats)
counts = defaultdict(int)
for i, feat in enumerate(feats):
    progress.setPercentage(int(100 * i / nFeats))
    attrs = feat.attributes()
    clazz = tuple([attrs[i] for i in fieldIdxs])
    print clazz
    counts[clazz] += 1

for c in counts:
    writer.addRecord(list(c) + [counts[c]])

This was reported from the GIS:Stack Exchange forum (http://gis.stackexchange.com/questions/171002/proper-use-of-qgis-tool-frequency-analysis)