PyQGIS – How to Retrieve the Name of Group Containing a Layer in PyQGIS

group-layerpyqgis

I've been using the "Layer List" plugin (https://plugins.qgis.org/plugins/layerList/) that does a great job of creating a text file with all the layer in a qgs project file.

I want to extend it to get the group and subgroup that the layer is in.

The desired result will be

Provider,Group,Subgroup,Name, Path, Filename.ext

ogr,Administration, Land,CL_TENURE_POLYGON_DC,D:/GIS/Data/DSE/Vicmap/VMCLTENURE/,CL_TENURE_POLYGON_DC.tab

I assume the change would be

def loadActiveLayers(self): 
self.dlgCreate.listWidget.clear() # Clear the list widget before it is filled again
canvas = iface.mapCanvas()
activeLayers = canvas.layers() # Create list with all active layers
layers = u"# Layer List - QGIS Plugin by Klas Karlsson\n" # Create list header and "test" line in a text string
for layer in reversed(activeLayers): # Repeat for all layers in the list
    layerType = layer.type() # Is it Vector or Raster?
    layerSource = layer.publicSource() # path or command for the layer source
    provider = layer.providerType() # Example org, gdal, wms, wfs, postgres, etc
    if layerType == QgsMapLayer.VectorLayer:
    layers = layers + (u"%s,%s,%s\n" % (provider, layer.name(), layerSource))

after layerSource add something for group and subgroup (maybe .layerTreeRoot() from https://qgis.org/api/classQgsLayerTreeGroup.html)

    self.dlgCreate.listWidget.addItem(layer.name()) # Add the layer name to the list

self.dlgCreate.listWidget.addItem(layer.?

 if layerType == QgsMapLayer.RasterLayer:
    layers = layers + (u"%s,%s,%s\n" % (provider, layer.name(), layerSource))
    self.dlgCreate.listWidget.addItem(layer.name()) # Add the layer name to the list
return layers   # Send back all the layers in a text string ready to be saved to a file

Would other changes be required?

Best Answer

Instead of using the layers from the QgsMapCanvas you could better iterate the root of the layer tree view (QgsProject.instance().layerTreeRoot().children()) like I show in How to create a text file containing layer names in QGIS?. In this way you could have direct access to layer tree view groups and layers. Having a QgsLayerTreeLayer you can easily go to the QgsMapLayer by calling my_tree_layer.layer().

However, if you want to stick to the way you're iterating layers, then you can still access the group a layer is in:

my_layer = iface.activeLayer() # Just for you to test

root = QgsProject.instance().layerTreeRoot()
tree_layer = root.findLayer(my_layer.id())
if tree_layer:
    layer_parent = tree_layer.parent()

    if layer_parent: 
        print("Layer parent: {}".format(layer_parent.name() or 'root'))
        group_parent = layer_parent.parent() # If you want to go up another level

        if group_parent: 
            print("Group parent: {}".format(group_parent.name() or 'root'))

Since you would use this repeatedly, based on the code snippet above you could create a function that gets a map layer and gives you group and subgroup.

Related Solutions

[GIS] Adding group layer, renaming it from folder name, then adding layers to it from that folder, using ArcPy/Python

This should work; it worked for me. This will give you a group layer named by the folder and a layer with the name of the shapefile. I built off what artwork21 posted.

import os
import arcpy

WS = r'c:\test_define'
arcpy.env.workspace = "in_memory"

mxd = arcpy.mapping.MapDocument(r"c:\test_define\test_python_add2.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]

for (path, dirs, files) in os.walk(WS):
    for name in files:
        if name.endswith(".shp"):

            groupLayer = arcpy.mapping.Layer(r"c:\test_define\empty_group_layer.lyr")  
            arcpy.mapping.AddLayer(df, groupLayer, "BOTTOM")

            layers = arcpy.mapping.ListLayers(mxd)
            for layer in layers:
                if layer.isGroupLayer and layer.name == "New Group Layer":
                    layer.name = os.path.basename(path)

            newLayer = arcpy.mapping.Layer(os.path.join(path, name))
            arcpy.mapping.AddLayerToGroup(df, layer, newLayer, "BOTTOM")

mxd.save()

You have to make the shapefiles into layers and use AddLayerToGroup. If you want a single group layer for each folder you can recycle this code and modify the os.walk to check for folders with .shp's and go from there. Although, I would recommend trying to contain all these shapefiles into a geodatabase with a proper naming structure and metadata to fit your needs.

To elaborate on the nonrepeating,

import arcpy
import os 

WS = r'c:\test_define'
arcpy.env.workspace = "WS"
mxd = arcpy.mapping.MapDocument(r"c:\test_define\test_python_add2.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
groupLayer = arcpy.mapping.Layer(r"c:\test_define\empty_group_layer.lyr")

for (path, dirs, files) in os.walk(WS):
    for name in files:
        if name.endswith(".shp"):

            layers = arcpy.mapping.ListLayers(mxd)
            name_list = []
            for layer in layers:
                if layer.isGroupLayer:
                    name_list.append(layer.name)

            if os.path.basename(path) not in name_list:
                arcpy.mapping.AddLayer(df, groupLayer, "BOTTOM")
                layers = arcpy.mapping.ListLayers(mxd)
                for layer in layers:
                    if layer.isGroupLayer and layer.name == "New Group Layer":
                        layer.name = os.path.basename(path)
                        newLayer = arcpy.mapping.Layer(os.path.join(path, name))
                        arcpy.mapping.AddLayerToGroup(df, layer, newLayer, "BOTTOM")

            if os.path.basename(path) in name_list:
                layers = arcpy.mapping.ListLayers(mxd)
                for layer in layers:
                    if layer.isGroupLayer and layer.name == os.path.basename(path):
                        newLayer = arcpy.mapping.Layer(os.path.join(path, name))
                        arcpy.mapping.AddLayerToGroup(df, layer, newLayer, "BOTTOM")


mxd.save()

This will check to see if a group layer already exists and will add to it, if so. Else, it will create a new group layer and add the layer.

[GIS] Batch add column to layers and add layer prefix in PyQGIS

You can achieve it by running the following code snippet in the QGIS Python console:

from PyQt4.QtCore import QVariant
for layer in QgsMapLayerRegistry.instance().mapLayers().values():
    prefix = layer.name().split("_")[0]
    res = layer.dataProvider().addAttributes([QgsField("density", QVariant.String)])
    layer.updateFields()
    fieldIndex = layer.dataProvider().fieldNameIndex( "density" )
    attrFeatMap = {}
    attrMap = { fieldIndex : prefix }
    for feature in layer.getFeatures():
        attrFeatMap[ feature.id() ] = attrMap
    layer.dataProvider().changeAttributeValues( attrFeatMap )

I assume the only layers you have loaded in the QGIS ToC are those you want to modify. Otherwise, you would need to validate things like the layer type (i.e., you don't want the script to run on raster layers).

The script iterates through layers loaded into QGIS, extracts the prefix from their names, creates the text field density, builds a dictionary like this:

{ featureId : { fieldIndex : value } }

for each feature, and finally, applies the dictionary to change features' density values.

enter image description here

Let me know if something is not clear.

Best Answer

Related Solutions

[GIS] Adding group layer, renaming it from folder name, then adding layers to it from that folder, using ArcPy/Python

[GIS] Batch add column to layers and add layer prefix in PyQGIS

Related Question