QGIS – Exporting Selected Features to Shapefile Using PyQGIS

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I am trying to develop a script to export selected features on a layer to enable some automation.

So far I have used this formula to import a layer and run a query. This ends up with features being selected on the layer.

See result:

All good so far.

I now try to use the below script, found in a previous similar question:
QGIS Export Shapefile using PyQgis

It worked for the users in the post, however this returns the following error for me:

I am quite new to Python so am not quite sure what's wrong. It is saying name 'i' is not defined, but I'm not sure what 'i' is trying to refer to?

I'm using QGIS 2.18.20.

Best Answer

The i in the post you linked to was referencing all layers that were loaded. So the code was iterating through each layer and saving their selected features.

Since you're only interested in one layer, replace i with layer and add the boolean selection parameter onlySelected:

_writer = QgsVectorFileWriter.writeAsVectorFormat(layer, 'C:/Datasets/South Oxfordshire Clipped LR INSPIRE.shp', "utf-8", None, "ESRI Shapefile", onlySelected=True)

Related Solutions

[GIS] Run QGIS layer Action on all selected features

You can create and run various actions from the Attribute Table for each feature. If you go to Layer Properties > Actions and add a new action, there is an option which allows you to run the action from the attribute table:

Once you have created an action, you can choose to show it as a combo box:

Now when you open your attribute table, you can see a new field containing the actions:

If you want your action to be run on multiple selected features, you will need to include this into your action (if possible). In my example, I am using Python to print the values from the first field for all selected features. So if I select multiple features and then click on any action combo box, it will print the values of the selected features:

However, there seems to be a Run layer action when you right-click an attribute but unfortunately, I can't seem to find much information concerning this. I have posted this as a new question as I am also curious:

What is this 'Run layer action' and how to use it?

PyQGIS – Running QGIS Algorithms with Selected Features Using PyQGIS

For only use selected feature use QgsProcessingFeatureSourceDefinition

https://qgis.org/api/classQgsProcessingFeatureSourceDefinition.html

your code,but the input is only selected features

import processing
input_vlayer = 'Some path'
intersect_vlayer = 'Some path'

input_vlayer = iface.addVectorLayer(input_vlayer,  'input_vlayer', 'ogr')
intersect_vlayer = iface.addVectorLayer(intersect_vlayer,  
                                       'intersect_vlayer', 'ogr')


for i in range(5):

    # Select the features
    intersect_vlayer.select(i)
    # Set input params
    params = {'INPUT':input_vlayer,
              'PREDICATE':0,
              'INTERSECT':QgsProcessingFeatureSourceDefinition(intersect_vlayer.id(), True), # USE HERE THE SELECTED FEATURES
              'METHOD':0}
    result = processing.run("qgis:selectbylocation", params)

    # Remove the current selection and then pass to the next one
    intersect_vlayer.removeSelection()

Best Answer

Related Solutions

[GIS] Run QGIS layer Action on all selected features

PyQGIS – Running QGIS Algorithms with Selected Features Using PyQGIS

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