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I have a plugin with my own map canvas and I create a button in order to remove all the layers visible or opened in map canvas. I use this lines:

QgsMapLayerRegistry.instance().removeAllMapLayers()
self.canvas.refresh() 

And it works but I noted that the layers are not in canvas but exist even that, I think they are in memory. How can I permanently remove the layers?

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  • How are you suspecting they are still in memory, can you expand more about this?
    – artwork21
    Oct 21, 2015 at 11:43
  • The layers are removed of visual field, but when I use self.canvas.layerCount() to count the number of layers in canvas, they still give me the number of layers that I removed. Oct 21, 2015 at 11:45
  • They are perhaps still stored within the layer registry. This post might help in purging the removed layers: Is there a purge function to remove layers from a qgs file which are not present in the Layers pane?
    – Joseph
    Oct 21, 2015 at 11:48
  • When I add a layer using QgsMapLayerRegistry.instance().addMapLayer(layerName) method and remove it using QgsMapLayerRegistry.instance().removeAllMapLayers() I get a count of 0. How are you adding your layers? Is the returned count for all the layers that were there before or just one or two?
    – artwork21
    Oct 21, 2015 at 12:01
  • Yes I am using QgsMapLayerRegistry.instance().addMapLayer(rlayer) and then self.canvas.setExtent(rlayer.extent()) but when I try to remove, it removes the map but the count is never 0. The count is the number of layers that were added. Oct 21, 2015 at 12:24

1 Answer 1

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I found a solution. I could not to change the result obtained by self.canvas.layerCount() but if I use QgsMapLayerRegistry.instance().count() I get 0 if the layers are removed. So it is what I need.

Thanks for the help.

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  • You've asked quite a lot of questions but barely accepted any. Did none of the answers helped? You can atleast accept your own answers.
    – user35594
    Mar 5, 2016 at 20:45

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