arcpy replace text placeholder

Question

I need to be able to walk through many mxds to replace text strings but able to skip a character place. For example, replace:

'area %d'

with

'area %d - this is some other text'

output:

'area 2'

'area 2 - this is some example text'

'area 3'

'area 3 - this is some example text'

This is what I have so far. It works for replace a specific string but I have not been able to figure out the placeholder variable.

import os
import arcpy

mxd_path = r'C:\Users\username\Desktop\test'

for dirpath, dirnames, filenames in os.walk(mxd_path):
    for filename in filenames:
        fullPath = os.path.join(dirpath, filename)
        basename, extension = os.path.splitext(filename)
        if extension.lower() == ".mxd":
            has_data_source = False
            mxd = arcpy.mapping.MapDocument(fullPath)
            for elm in arcpy.mapping.ListLayoutElements(mxd, 'TEXT_ELEMENT'):
                elm.text = elm.text.replace('area %d',
                                            'area %d - this is some other text')

            mxd.save()
            del mxd

Answer 1

If you are just adding text to the end of an existing string, then just concatenate text onto the end:

elm.text = "{0} - Additional text goes here".format(elm.text)

So Area 1 becomes Area 1 - Additional text goes here