Setting scale for data driven pages

Question

I'm trying to use DDP to produce a map book for a series of works. Each item of work is a feature in a polyline feature class, and a copy of the class is being used to define my DDPs. I already have set up dynamic text, page definition queries etc.

As the work lines are variable in length, I want to constrain my map scale so that they are not zoomed in or out too far. My code:

import arcpy
from arcpy import env

env.workspace = r"U:"
mxd = arcpy.mapping.MapDocument(r"U:\EMS.mxd")
df = arcpy.mapping.ListDataFrames(mxd)[0]
ddp = mxd.dataDrivenPages
indexLayer = ddp.indexLayer

# def ddpScale():
#     if df.scale < 6000:
#         df.scale = 6000
#     elif df.scale > 10000:
#         df.scale = 10000
#     else:
#     df.scale = 10000

for i in range(1, mxd.dataDrivenPages.pageCount + 1):
    mxd.dataDrivenPages.currentPageID = i
    for scale in df.scale:
        if df.scale < 6000:
            df.scale = 6000
        elif df.scale > 10000:
            df.scale = 10000
        else:
            df.scale = 10000
    #df.scale = ddpScale

ddp.exportToPDF(r"U:\test.pdf")

del mxd

The commented out lines were my attempt to define a function for setting the scale, but I opted for a elif statement instead. I basically want any pages with a scale less than 1:6000 to be 1:6000, and all others to be 1:10,0000.

As an addition, I would like lines that are above 1:10,000 originally to be split across multiple pages as needed.

How would I got about setting the scale in this manner?

The error I am getting:

Traceback (most recent call last):
  File "C:/XXXddp.py", line 
20, in <module>
    for scale in df.scale:
TypeError: 'float' object is not iterable

Answer 1

An alternative is to use a field with scales as Data Driven Scale Field:

When you specify a Data Driven Scale field, values from this field define the map scale of the detail data frame for each page in the Data Driven Pages series

The field can be calculated using arcpy by the extent of each feature:

import arcpy

fc = "Areas" #Change to match your fc
scalefield = "Scale" #Add this field before executing the code.

with arcpy.da.UpdateCursor(fc,["SHAPE@",scalefield]) as cursor:
    for row in cursor:
        ext = row[0].extent
        maxdiffxy = max([ext.XMax-ext.XMin,ext.YMax-ext.YMin]) #Max width or height of feature
        if maxdiffxy<2500: #If smaller than 2500 meters, use 6000 scale. Will have to be adjusted
            row[1] = 6000
        else:
            row[1] = 10000
        cursor.updateRow(row)