Resequencing Legend Items using ArcPy?

Question

I create various layers programmatically using ArcPy.

I can adjust how the layers are sequenced using the arcpy.mapping.MoveLayer command.

However, I want to have the legend reflect a different order. I have yet to figure out how to do this in Python.

I have tried using legend.autoAdd=True or False. I think I am close in using:

legend=arcpy.mapping.ListLayoutElements(mxd,"LEGEND_ELEMENT","My Legend") [0]

and then legend.items.something.

I have four legend items A, B, C, and D which appear incorrectly as D, C, A, B.

Can anyone provde a link to code examples or better documentation?

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This question was originally posed for ArcGIS 10.0 but another question (Moving legend items up and down with arcpy) using ArcGIS 10.2 has been merged into it so answers using any version from and including 10.0 should be acceptable.

Answer 1

With the AddLayer method you cannot be more precise than "TOP" or "BOTTOM" as shown above.

However, if you use the InsertLayer method (ESRI Help Pages), you can specify a reference layer (or multiple reference layers) and add your new layer in reference to that.

import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "County Maps")[0]
refLayer = arcpy.mapping.ListLayers(mxd, "Lakes", df)[0]
insertLayer = arcpy.mapping.Layer(r"C:\Project\Data\Rivers.lyr")
arcpy.mapping.InsertLayer(df, refLayer, insertLayer, "BEFORE")
mxd.saveACopy(r"C:\Project\Project2.mxd")
del mxd, insertLayer

Answer 2

As near as I can tell (from working with the mapping class a couple of days ago), legend items themselves are created only using auto-add. I have found no methods for manipulating layer names and positions in the legend directly. The mapping class is not all-powerful in my experience, and is generally only as useful as the .mxd it is combined with. Most fine-tuning seems to be best left to ArcMap's UI.

That being said, you can order your elements by adding them to your map in the same order they are to appear in your legend.

(This is taken mostly from arcpy's documentation):

df = arcpy.mapping.ListDataFrames(mxd, "New Data Frame")[0]  
lyrA = arcpy.mapping.Layer(r"C:\Path\LayerA.lyr")  
lyrB = arcpy.mapping.Layer(r"C:\Path\LayerB.lyr")  
lyrC = arcpy.mapping.Layer(r"C:\Path\LayerC.lyr")  
lyrD = arcpy.mapping.Layer(r"C:\Path\LayerD.lyr")  
legend = arcpy.mapping.ListLayoutElements(mxd, "LEGEND_ELEMENT", "Legend")[0]  
legend.autoAdd = True  
arcpy.mapping.AddLayer(df, lyrA, "BOTTOM")  
arcpy.mapping.AddLayer(df, lyrB, "BOTTOM")  
arcpy.mapping.AddLayer(df, lyrC, "BOTTOM")  
arcpy.mapping.AddLayer(df, lyrD, "BOTTOM")  
mxd.save()  
del mxd

Answer 3

The legend will always reflect the draw order of the map, AFAIK. You can change the draw order using arcpy.mapping.MoveLayer. There is a code example from the ESRI help

import arcpy mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd") df = arcpy.mapping.ListDataFrames(mxd, "County Maps")[0] for lyr in arcpy.mapping.ListLayers(mxd, "", df): if lyr.name.lower() == "rivers": moveLayer = lyr if lyr.name.lower() == "lakes": refLayer = lyr arcpy.mapping.MoveLayer(df, refLayer, moveLayer, "BEFORE") mxd.saveACopy(r"C:\Project\Project2.mxd") del mxd