Using RemoveLayer in arcpy.mapping?

Question

I am trying to use RemoveLayer within the mapping module, but seem to be getting mixed results. I do the following to add a layer to the map

mxd = arcpy.mapping.MapDocument("CURRENT") # define map document
lyr = arcpy.mapping.Layer(r"C:\test.lyr") # define layer object
df = arcpy.mapping.ListDataFrames(mxd) # list data frames
arcpy.mapping.AddLayer(df[0],lyr) #  add layer 

Now that the layer is added, I am trying to use arcpy.mapping.RemoveLayer to remove the layer from the map. I do the following.

arcpy.mapping.RemoveLayer(df[0],lyr)

But this doesn't work. The layers still exist in the map. But if I try the following code where I list the layers and then loop through and use RemoveLayer, it works now. Why?

lyrlist = arcpy.mapping.ListLayers(mxd)
for i in lyrlist:
    arcpy.mapping.RemoveLayer(df[0],i)

Is this because Layer objects don't work with RemoveLayer for some reason?

Answer 1

You're still referencing the layer file with your variable lyr. You'll need to find it in your mxd before you can remove it.

Maybe something like this:

lyrlist = arcpy.mapping.ListLayers(mxd)
lyr = [l for l in lyrlist if l.name == "test"] [0]
arcpy.mapping.RemoveLayer(df[0],lyr)