# -*- coding: utf-8 -*- """ *************************************************************************** vector.py --------------------- Date : February 2013 Copyright : (C) 2013 by Victor Olaya Email : volayaf at gmail dot com *************************************************************************** * * * This program is free software; you can redistribute it and/or modify * * it under the terms of the GNU General Public License as published by * * the Free Software Foundation; either version 2 of the License, or * * (at your option) any later version. * * * *************************************************************************** """ __author__ = 'Victor Olaya' __date__ = 'February 2013' __copyright__ = '(C) 2013, Victor Olaya' # This will get replaced with a git SHA1 when you do a git archive __revision__ = '$Format:%H$' from processing.core.ProcessingConfig import ProcessingConfig from qgis.core import * from PyQt4.QtCore import * def features(layer): '''this returns an iterator over features in a vector layer, considering the selection that might exist in the layer, and the configuration that indicates whether to use only selected feature or all of them. This should be used by algorithms instead of calling the QGis API directly, to ensure a consistent behaviour across algorithms''' class Features(): def __init__(self, layer): self.layer = layer self.iter = layer.getFeatures() self.selection = False; if ProcessingConfig.getSetting(ProcessingConfig.USE_SELECTED): self.selected = layer.selectedFeatures() if len(self.selected) > 0: self.selection = True self.idx = 0; def __iter__(self): return self def next(self): if self.selection: if self.idx < len(self.selected): feature = self.selected[self.idx] self.idx += 1 return feature else: raise StopIteration() else: if self.iter.isClosed(): raise StopIteration() f = QgsFeature() if self.iter.nextFeature(f): return f else: self.iter.close() raise StopIteration() def __len__(self): if self.selection: return int(self.layer.selectedFeatureCount()) else: return int(self.layer.featureCount()) return Features(layer) def uniqueValues(layer, attribute): '''Returns a list of unique values for a given attribute. Attribute can be defined using a field names or a zero-based field index. It considers the existing selection''' values = [] fieldIndex = resolveFieldIndex(layer, attribute) feats = features(layer) for feat in feats: if feat.attributes()[fieldIndex] not in values: values.append(feat.attributes()[fieldIndex]) return values def resolveFieldIndex(layer, attr): '''This method takes an object and returns the index field it refers to in a layer. If the passed object is an integer, it returns the same integer value. If the passed value is not an integer, it returns the field whose name is the string representation of the passed object. Ir raises an exception if the int value is larger than the number of fields, or if the passed object does not correspond to any field''' if isinstance(attr, int): return attr else: index = layer.fieldNameIndex(unicode(attr)) if index == -1: raise ValueError('Wrong field name') return index def values(layer, *attributes): '''Returns the values in the attributes table of a vector layer, for the passed fields. Field can be passed as field names or as zero-based field indices. Returns a dict of lists, with the passed field identifiers as keys. It considers the existing selection. It assummes fields are numeric or contain values that can be parsed to a number''' ret = {} for attr in attributes: index = resolveFieldIndex(layer, attr) values = [] feats = features(layer) for feature in feats: try: v = float(feature.attributes()[index]) values.append(v) except: values.append(None) ret[attr] = values; return ret def spatialindex(layer): '''Creates a spatial index for the passed vector layer''' idx = QgsSpatialIndex() feats = features(layer) for ft in feats: idx.insertFeature(ft) return idx def createUniqueFieldName(fieldName, fieldList): shortName = fieldName[:10] if len(fieldList) == 0: return shortName fieldNames = [f.name() for f in fieldList] if shortName not in fieldNames: return shortName shortName = fieldName[:8] + "_1" changed = True while changed: changed = False for n in fieldList: if n == shortName: # create unique field name num = int(shortName[-1:]) if num < 9: shortName = shortName[:8] + "_" + str(num + 1) else: shortName = shortName[:7] + "_" + str(num + 1) changed = True return shortName def findOrCreateField(layer, fieldList, fieldName, fieldLen=24, fieldPrec=15): idx = layer.fieldNameIndex(fieldName) if idx == -1: fn = createUniqueFieldName(fieldName, fieldList) field = QgsField(fn, QVariant.Double, "", fieldLen, fieldPrec) idx = len(fieldList) fieldList.append(field) return idx, fieldList def extractPoints(geom): points = [] if geom.type() == QGis.Point: if geom.isMultipart(): points = geom.asMultiPoint() else: points.append(geom.asPoint()) elif geom.type() == QGis.Line: if geom.isMultipart(): lines = geom.asMultiPolyline() for line in lines: points.extend(line) else: points = geom.asPolyline() elif geom.type() == QGis.Polygon: if geom.isMultipart(): polygons = geom.asMultiPolygon() for poly in polygons: for line in poly: points.extend(line) else: polygon = geom.asPolygon() for line in polygon: points.extend(line) return points def simpleMeasure(geom, method=0, ellips=None, crs=None): # method defines calculation type: # 0 - layer CRS # 1 - project CRS # 2 - ellipsoidal if geom.wkbType() in [QGis.WKBPoint, QGis.WKBPoint25D]: pt = geom.asPoint() attr1 = pt.x() attr2 = pt.y() elif geom.wkbType() in [QGis.WKBMultiPoint, QGis.WKBMultiPoint25D]: pt = inGeom.asMultiPoint() attr1 = pt[0].x() attr2 = pt[0].y() else: measure = QgsDistanceArea() if method == 2: measure.setSourceCrs(crs) measure.setEllipsoid(ellips) measure.setEllipsoidalMode(True) attr1 = measure.measure(geom) if geom.type() == QGis.Polygon: attr2 = measure.measurePerimeter(geom) else: attr2 = None return (attr1, attr2) def getUniqueValues(layer, fieldIndex): values = [] feats = features(layer) for feat in feats: if feat.attributes()[fieldIndex] not in values: values.append(feat.attributes()[fieldIndex]) return values def getUniqueValuesCount(layer, fieldIndex): return len(getUniqueValues(layer, fieldIndex)) def combineVectorFields(layerA, layerB): '''Create single field map from two input field maps''' fields = [] fieldsA = layerA.dataProvider().fields() fields.extend(fieldsA) namesA = [unicode(f.name()).lower() for f in fieldsA] fieldsB = layerB.dataProvider().fields() for field in fieldsB: name = unicode(field.name()).lower() if name in namesA: idx=2 newName = name + "_" + unicode(idx) while newName in namesA: idx += 1 newName = name + "_" + unicode(idx) field = QgsField(newName, field.type(), field.typeName()) fields.append(field) return fields