I'm writing Python code for ArcGIS using the arcpy library and now I'm experiencing a little problem with labels. In fact I'm not able to rotate them in layout via arcpy (I should rotate all labels of 90 degrees). I found a way to display correct field, round the number, but not to position the label correctly.
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if it's possible for example to copy the label style from an external file?
you should be able to just use Save As Layer File to create your *.lyr with rotated labels.
The *.lyr file can be added into your map using arcpy.mapping.AddLayer and then use arcpy.mapping.replaceDataSource to change that layer's source to the dataset whose labels you want to see rotated.