ArcGIS 10.0 – Change Layer Symbology in ArcMap with ArcPy

arcgis-10.0arcpysymbology

In an active ArcMap session – I want to change the symbology of a layer which is repeated multiple times in the mxd. Can I do this?

The basic code I have for getting the layers is below. This is running within ArcMap (not as a .py script)

myMXD = arcpy.mapping.MapDocument("Current")
lstDataFrames=arcpy.mapping.ListDataFrames(myMXD)
lstLayers=arcpy.mapping.ListLayers(myMXD)

hazardLayer=arcpy.mapping.ListLayers(myMXD,'*Haz*')

allFrames=arcpy.mapping.ListDataFrames(myMXD)

for dataFrame in allFrames:
    myMXD.activeView=dataFrame
    for mapLayer in hazardLayer:
        mapLayer.visible=False

This just changes the visibility to off…can I change the color for example to some RGB value?

Best Answer

You could use the Apply Symbology From Layer tool.

This tool applies the symbology from a layer to the Input Layer. It can be applied to feature, raster, network analysis, TIN, and geostatistical layer files or layers in the ArcMap table of contents. This tool is primarily for use in scripts or ModelBuilder.

Related Solutions

[GIS] Using Unique Values Symbology in ArcPy

Try this code and then re-open your MXD in ArcMap and I think you should see your new symbology.

import arcpy
mxd = arcpy.mapping.MapDocument("D:\\ArcGIS_Data\\data\\y1.mxd")
lyr = arcpy.mapping.ListLayers(mxd, "Population")[0]
if lyr.symbologyType == "UNIQUE_VALUES":
  lyr.symbology.valueField = "SUB_REGION"
  lyr.symbology.addAllValues()
mxd.save()
del mxd

As @Roland commented you were running your code as a process separate from your server, which was reading the map document off disk. Although your code modified the document, it hadn't saved the changes to the mxd file (which is what the server would show).

[GIS] Iterating through all geometries using ArcPy search cursor

You are collecting the extents for each polygon correctly, but need to zoom to them within the loop, or a later loop depending on what you want to do.

For example to zoom in the same loop as the search cursor e.g.

with arcpy.da.SearchCursor(SelLayer,"SHAPE@") as SCur:
    for feat in SCur:
        # I'm going to assume polygon/polyline
        Envelopes.append(feat[0].extent) # grab the envelope 
        df.extent = feat[0].extent # first extent # <- Move this into the loop
        arcpy.RefreshActiveView()

        time.sleep(5) # Wait 5 Seconds. 
        # ^ Replace this with what you want to do at each poly.

Best Answer

Related Solutions

[GIS] Using Unique Values Symbology in ArcPy

[GIS] Iterating through all geometries using ArcPy search cursor

Related Question