QGIS API Documentation 3.27.0-Master (9c08adf5ef)
qgsaggregatecalculator.h
Go to the documentation of this file.
1/***************************************************************************
2 qgsaggregatecalculator.h
3 ------------------------
4 begin : May 2016
5 copyright : (C) 2016 by Nyall Dawson
6 email : nyall dot dawson at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
18#ifndef QGSAGGREGATECALCULATOR_H
19#define QGSAGGREGATECALCULATOR_H
20
21#include "qgis_core.h"
25#include "qgsfeaturerequest.h"
26#include <QVariant>
27#include "qgsfeatureid.h"
28
29
31class QgsExpression;
32class QgsVectorLayer;
34
44class CORE_EXPORT QgsAggregateCalculator
45{
46 public:
47
54 {
56 QString function;
58 QString name;
60 QSet<QVariant::Type> supportedTypes;
61 };
62
68 {
90 StringConcatenateUnique
91 };
92
95 {
96
103 QString filter;
104
110 QString delimiter;
111
117 };
118
124
130 QString lastError() const { return mLastError; }
131
135 const QgsVectorLayer *layer() const;
136
141 void setParameters( const AggregateParameters &parameters );
142
148 void setFilter( const QString &filterExpression ) { mFilterExpression = filterExpression; }
149
156 void setFidsFilter( const QgsFeatureIds &fids );
157
162 QString filter() const { return mFilterExpression; }
163
169 void setDelimiter( const QString &delimiter ) { mDelimiter = delimiter; }
170
175 QString delimiter() const { return mDelimiter; }
176
188 QVariant calculate( Aggregate aggregate, const QString &fieldOrExpression,
189 QgsExpressionContext *context = nullptr, bool *ok = nullptr, QgsFeedback *feedback = nullptr ) const;
190
197 static Aggregate stringToAggregate( const QString &string, bool *ok = nullptr );
198
203 static QString displayName( Aggregate aggregate );
204
210 static QList< QgsAggregateCalculator::AggregateInfo > aggregates();
211
212 private:
213
215 const QgsVectorLayer *mLayer = nullptr;
216
218 QString mFilterExpression;
219
222
224 QString mDelimiter;
225
227 QgsFeatureIds mFidsFilter;
228
229 //trigger variable
230 bool mFidsSet = false;
231
232 mutable QString mLastError;
233
234 static QgsStatisticalSummary::Statistic numericStatFromAggregate( Aggregate aggregate, bool *ok = nullptr );
235 static QgsStringStatisticalSummary::Statistic stringStatFromAggregate( Aggregate aggregate, bool *ok = nullptr );
236 static QgsDateTimeStatisticalSummary::Statistic dateTimeStatFromAggregate( Aggregate aggregate, bool *ok = nullptr );
237
238 static QVariant calculateNumericAggregate( QgsFeatureIterator &fit, int attr, QgsExpression *expression,
240
241 static QVariant calculateStringAggregate( QgsFeatureIterator &fit, int attr, QgsExpression *expression,
243
244 static QVariant calculateDateTimeAggregate( QgsFeatureIterator &fit, int attr, QgsExpression *expression,
246 static QVariant calculateGeometryAggregate( QgsFeatureIterator &fit, QgsExpression *expression, QgsExpressionContext *context );
247
248 static QVariant calculateArrayAggregate( QgsFeatureIterator &fit, int attr, QgsExpression *expression,
249 QgsExpressionContext *context );
250
251 static QVariant calculate( Aggregate aggregate, QgsFeatureIterator &fit, QVariant::Type resultType, int userType,
252 int attr, QgsExpression *expression,
253 const QString &delimiter,
254 QgsExpressionContext *context, bool *ok = nullptr, QString *error = nullptr );
255 static QVariant concatenateStrings( QgsFeatureIterator &fit, int attr, QgsExpression *expression,
256 QgsExpressionContext *context, const QString &delimiter, bool unique = false );
257
258 QVariant defaultValue( Aggregate aggregate ) const;
259};
260
261#endif //QGSAGGREGATECALCULATOR_H
Utility class for calculating aggregates for a field (or expression) over the features from a vector ...
void setFilter(const QString &filterExpression)
Sets a filter to limit the features used during the aggregate calculation.
void setDelimiter(const QString &delimiter)
Sets the delimiter to use for joining values with the StringConcatenate aggregate.
QString lastError() const
Returns the last error encountered during the aggregate calculation.
QString filter() const
Returns the filter which limits the features used during the aggregate calculation.
Aggregate
Available aggregates to calculate.
@ StDev
Standard deviation of values (numeric fields only)
@ StringMaximumLength
Maximum length of string (string fields only)
@ ThirdQuartile
Third quartile (numeric fields only)
@ Range
Range of values (max - min) (numeric and datetime fields only)
@ ArrayAggregate
Create an array of values.
@ InterQuartileRange
Inter quartile range (IQR) (numeric fields only)
@ FirstQuartile
First quartile (numeric fields only)
@ Median
Median of values (numeric fields only)
@ GeometryCollect
Create a multipart geometry from aggregated geometries.
@ CountMissing
Number of missing (null) values.
@ StDevSample
Sample standard deviation of values (numeric fields only)
@ Majority
Majority of values.
@ StringConcatenate
Concatenate values with a joining string (string fields only). Specify the delimiter using setDelimit...
@ Mean
Mean of values (numeric fields only)
@ StringMinimumLength
Minimum length of string (string fields only)
@ CountDistinct
Number of distinct values.
@ Minority
Minority of values.
QString delimiter() const
Returns the delimiter used for joining values with the StringConcatenate aggregate.
Statistic
Enumeration of flags that specify statistics to be calculated.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Class for parsing and evaluation of expressions (formerly called "search strings").
Wrapper for iterator of features from vector data provider or vector layer.
Represents a list of OrderByClauses, with the most important first and the least important last.
Base class for feedback objects to be used for cancellation of something running in a worker thread.
Definition: qgsfeedback.h:45
Statistic
Enumeration of flags that specify statistics to be calculated.
Statistic
Enumeration of flags that specify statistics to be calculated.
Represents a vector layer which manages a vector based data sets.
QSet< QgsFeatureId > QgsFeatureIds
Definition: qgsfeatureid.h:37
Structured information about the available aggregates.
QString name
A translated, human readable name.
QSet< QVariant::Type > supportedTypes
This aggregate function can only be used with these datatypes.
QString function
The expression function.
A bundle of parameters controlling aggregate calculation.
QString filter
Optional filter for calculating aggregate over a subset of features, or an empty string to use all fe...
QString delimiter
Delimiter to use for joining values with the StringConcatenate aggregate.
QgsFeatureRequest::OrderBy orderBy
Optional order by clauses.