Select several layers by name using an expression

Question

I'm am new to using PyQGIS and this question has been answered in various forms already, however not specifically the way I need it; I have a big QGIS project with several layers with similar, but not the same names (e.g. names containing certain keywords like "nationalpark", "flooding zone" etc.), and I want to apply Styles to all layers with names containing certain keywords, e.g. "nationalpark". I found out that I can select layers using e.g.

layers = QgsProject.instance().mapLayersByName('my layer name')

but how can I select layers by non-specific names, containing certain keywords?

Answer 1

You can use Python's in operator to retrieve the layers in your project whose names contain a keyword/words.

E.g.

key_word = "flooding zone"

layers = [lyr for lyr in QgsProject.instance().mapLayers().values() if key_word in lyr.name()]

print(layers)

for lyr in layers:
    # Do something with layer...
    lyr.loadNamedStyle('path/to/style.qml')

The mapLayers() method of QgsProject returns a dictionary, so we use Python's values() method to access the QgsMapLayer objects.