fieldName = self.getParameterValue(self.FIELD_NAME) fieldLength = self.getParameterValue(self.FIELD_LENGTH) fieldPrecision = self.getParameterValue(self.FIELD_PRECISION) output = self.getOutputFromName(self.OUTPUT_LAYER) layer =QGisLayers.getObjectFromUri(self.getParameterValue(self.INPUT_LAYER)) provi...
第8行QString( "field=id:integer&field=name:string(50)&" )是定义的图层字段,这也是我觉得很方便的一个地方,多个字段用"&" 进行连接,完整形式为 field=name:type(length,precision),从参数看不仅可以定义长度还可以定义其精度; 第10行QString( "index=yes&" )是定义空间索引,对于...
第8行QString( "field=id:integer&field=name:string(50)&" )是定义的图层字段,这也是我觉得很方便的一个地方,多个字段用"&" 进行连接,完整形式为field=name:type(length,precision),从参数看不仅可以定义长度还可以定义其精度; 第10行QString( "index=yes&" )是定义空间索引,对于数据量较大的图层很有用;...
Next, weopen the attribute tableand create the new x , y values 1)Fill output field name 2)change the output field type to decimal number (real) 3)change the field length 4)from the middle box, choose geology ➡️ x➡️点击OK 我们就会得到crs=27700 (新的坐标系)的点坐标列,同理...
Specifies that the layer will be constructed with a spatial index - field=name:type(length,...
QgsFields负责属性字段的管理,通常包含多个QgsField,每个QgsField包括以下属性: Q_PROPERTY(boolisNumeric READ isNumeric ) Q_PROPERTY(boolisDateOrTime READ isDateOrTime ) Q_PROPERTY(intlength READ length WRITE setLength ) Q_PROPERTY(intprecision READ precision WRITE setPrecision ) ...
If you want to update the values of the existing field, check the “Update existing field” box. Click the “OK” button to execute the calculation. Examples of Field Calculator expressions that you can use in QGIS: Calculate the length of a line feature in meters:$length ...
field=name:type(length,precision) Specifies an attribute of the layer. The attribute has a name, and optionally a type (integer, double, or string), length, and precision. There may be multiple field definitions. The following example of a URI incorporates all these options ...
QgsFields提供append函数添加属性字段,每个字段的具体数据由QgsField对象持有。 QgsField f1;f1.setName(QStringLiteral("name"));f1.setType(QVariant::Int);f1.setTypeName(QStringLiteral("typename"));f1.setLength(5);f1.setPrecision(1);f1.setComment(QStringLiteral("comment"));mAttributeFieds.appen...
QgsFieldExpression(shortest_path_length)) #应用渲染规则 symbol.changeSymbolLayer(0,symbol_layer) #清理QGIS环境 QgsApplication.exitQgis() 14.3解释解释 1.初始化初始化QGIS环境环境:设置QGIS的前缀路径,并初始化QGIS应用。 2.加载网络图层加载网络图层:使用QgsVectorLayer加载网络数据。 3.构建网络图构建网络图:...