Getting rid of warning messages when selecting by location using PyQGIS?

Question

I am running a Python script in QGIS 2.18.26 and I have a select by location with a code like that:

indir = "C:/Infolder/"  
outdir = "C:/Outfolder/"  

os.chdir(indir)  

for fname in glob.glob("*.shp"):  
    layerResult = processing.getObject(fname)

    QgsMapLayerRegistry.instance().addMapLayer(layerResult)
    processing.runalg("qgis:selectbylocation", layerResult, "C:/SomePolygon.shp", u'within',0,0)

    result= outdir + 'Test' + fname
    processing.runalg('qgis:saveselectedfeatures', layerResult, result)
    #processing.load(result)
    QgsMapLayerRegistry.instance().removeMapLayers( [layerResult.id()] )

In case there is no section, I receive a pop-up window as follows:

I want to avoid that pop-up window because it slows down the whole process.

Can you please advise how I can get rid of it?

Answer 1

You can add an if statement to check if any features are selected:

if layerResult.selectedFeatures():

If there are selected features then run the second algorithm otherwise do something else. So your script could look like:

indir = "C:/Infolder/"  
outdir = "C:/Outfolder/"  

os.chdir(indir)  

for fname in glob.glob("*.shp"):  
    layerResult = processing.getObject(fname)

    QgsMapLayerRegistry.instance().addMapLayer(layerResult)
    processing.runalg("qgis:selectbylocation", layerResult, "C:/SomePolygon.shp", u'within',0,0)

    if layerResult.selectedFeatures():
        result= outdir + 'Test' + fname
        processing.runalg('qgis:saveselectedfeatures', layerResult, result)
        #processing.load(result)
        QgsMapLayerRegistry.instance().removeMapLayers( [layerResult.id()] )
    else:
        # do something else