Preventing ArcPy from changing MXD extent?

Question

I want to process mxd datasources without changing the extent.

When I open the MXD in ArcMap and click full extent, I get 1:214,890, after I save and re-open in ArcMap I get what I saved with.

When I open the MXD with arcpy the scale changes to 1:570,396, so after processing and saving via arcpy it's zoomed further out when reopened in ArcMap.

df = arcpy.mapping.ListDataFrames(mxd)[0]
print df.extent

Answer 1

An alternative would be to hard wire the scale into your code before saving the mxd.

mxd = arcpy.mapping.MapDocument("Current")
df = arcpy.mapping.ListDataFrames(mxd)[0]
df.scale = "1:214,890"
arcpy.RefreshActiveView()
mxd.save()

Answer 2

Depending on what else you are planning to do in your script there are two approaches that I think would address this:

1. Use Fixed Scale on the Data Frame tab of the Properties of your data frame before you save in ArcMap:

2. Set the scale property on your data frame object explicitly within your script:

   df.scale = 214890

Without seeing a code snippet in your question it is hard to advise on why the scale may be changing in your code/configuration. I just ran a test here using ArcGIS 10.2.2 for Desktop where I:

1. Opened a test.mxd
2. Set the scale on its only data frame to 1:100,000
3. Checked the Data Frame tab of the Properties of the data frame to make sure it was set to Automatic
4. Saved and closed the map

5. Ran the code below from IDLE

   import arcpy

   mxd = arcpy.mapping.MapDocument(r"C:\temp\test.mxd")

   df = arcpy.mapping.ListDataFrames(mxd)[0]

   print df.scale

6. The value printed was:

   100000.0