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Make value field in 'Stats by category' optional

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If not set, only the feature counts for each category will
be calculated
This commit is contained in:
Nyall Dawson 2017-09-06 17:03:15 +10:00
parent 30c663eaef
commit ea2e537cd7
1 changed files with 52 additions and 24 deletions
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44
python/plugins/processing/algs/qgis/StatisticsByCategories.py
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@ -64,8 +64,9 @@ class StatisticsByCategories(QgisAlgorithm):
self.tr('Input vector layer'),
types=[QgsProcessing.TypeVector]))
self.addParameter(QgsProcessingParameterField(self.VALUES_FIELD_NAME,
self.tr('Field to calculate statistics on'),
parentLayerParameterName=self.INPUT))
self.tr(
'Field to calculate statistics on (if empty, only count is calculated)'),
parentLayerParameterName=self.INPUT, optional=True))
self.addParameter(QgsProcessingParameterField(self.CATEGORIES_FIELD_NAME,
self.tr('Field(s) with categories'),
parentLayerParameterName=self.INPUT,
@ -85,7 +86,10 @@ class StatisticsByCategories(QgisAlgorithm):
category_field_names = self.parameterAsFields(parameters, self.CATEGORIES_FIELD_NAME, context)
value_field_index = source.fields().lookupField(value_field_name)
if value_field_index >= 0:
value_field = source.fields().at(value_field_index)
else:
value_field = None
category_field_indexes = [source.fields().lookupField(n) for n in category_field_names]
# generate output fields
@ -101,7 +105,10 @@ class StatisticsByCategories(QgisAlgorithm):
field.setName(name)
fields.append(field)
if value_field.isNumeric():
if value_field is None:
field_type = 'none'
fields.append(QgsField('count', QVariant.Int))
elif value_field.isNumeric():
field_type = 'numeric'
fields.append(QgsField('count', QVariant.Int))
fields.append(QgsField('unique', QVariant.Int))
@ -140,11 +147,17 @@ class StatisticsByCategories(QgisAlgorithm):
fields.append(QgsField('mean_length', QVariant.Double))
request = QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry)
if value_field is not None:
attrs = [value_field_index]
else:
attrs = []
attrs.extend(category_field_indexes)
request.setSubsetOfAttributes(attrs)
features = source.getFeatures(request)
total = 50.0 / source.featureCount() if source.featureCount() else 0
if field_type == 'none':
values = defaultdict(lambda: 0)
else:
values = defaultdict(list)
for current, feat in enumerate(features):
if feedback.isCanceled():
@ -152,7 +165,10 @@ class StatisticsByCategories(QgisAlgorithm):
feedback.setProgress(int(current * total))
attrs = feat.attributes()
if True:
cat = tuple([attrs[c] for c in category_field_indexes])
if field_type == 'none':
values[cat] += 1
continue
if field_type == 'numeric':
if attrs[value_field_index] == NULL:
continue
@ -167,15 +183,14 @@ class StatisticsByCategories(QgisAlgorithm):
value = NULL
else:
value = attrs[value_field_index]
cat = tuple([attrs[c] for c in category_field_indexes])
values[cat].append(value)
else:
pass
(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, QgsWkbTypes.NoGeometry, QgsCoordinateReferenceSystem())
if field_type == 'numeric':
if field_type == 'none':
self.saveCounts(values, sink, feedback)
elif field_type == 'numeric':
self.calcNumericStats(values, sink, feedback)
elif field_type == 'datetime':
self.calcDateTimeStats(values, sink, feedback)
@ -184,6 +199,19 @@ class StatisticsByCategories(QgisAlgorithm):
return {self.OUTPUT: dest_id}
def saveCounts(self, values, sink, feedback):
total = 50.0 / len(values) if values else 0
current = 0
for cat, v in values.items():
if feedback.isCanceled():
break
feedback.setProgress(int(current * total) + 50)
f = QgsFeature()
f.setAttributes(list(cat) + [v])
sink.addFeature(f, QgsFeatureSink.FastInsert)
current += 1
def calcNumericStats(self, values, sink, feedback):
stat = QgsStatisticalSummary()