Free Frequency ... join the cause 

Blog Post created by Dan_Patterson Champion on Mar 3, 2016

Free Frequency...   


Announced  2017-04-15  ***Frequency is freed... version for ArcGIS Pro

Created        2016-03-02

Modified       2016-12-20  *** the shackles remain in 10.5 make it your resolution in 2017 to join the cause

References   many


Why is this tool only available at the Advanced license level???

Come on. That is lame. This type of question comes up time and again.

Select your options from the following request.


I have ...

    • two   - several   - many

columns containing class information with

    • the same   - different data types

and I want to combine them to produce a unique classification scheme and

    • count the number in each class
    • calculate some statistical value,
    • graph it.


Get the picture?  Sound familiar?

I will show the results of doing this type of analysis and provide an attachment for you to do it.

In ArcGIS, the Frequency tool produces these results


Now these results look similar...in fact identical, but created without using the frequency tool... but using tools provided within ArcMap itself.

Input arraySorted arraySummary

    A     B

   'a',   'c'

   'b',   'a'

   'c',   'b'

   'c',   'b'

   'b',   'a'

   'a',   'c'

   'b',   'a'

   'c',   'b'

   'b',   'a'

   'a',   'c'

   'a',   'a'

   'c',   'b'

   A     B    class row

   'a',   'a'     0       0

   'a',   'c'     1       1

   'a',   'c'     1

   'a',   'c'     1

   'b',   'a'     2       4

   'b',   'a'     2

   'b',   'a'     2

   'b',   'a'     2

   'c',   'b'     3       8

   'c',   'b'     3

   'c',   'b'     3

   'c',   'b'     3

combinations    class

  ( 'a',   'a' )              0

  ( 'a',   'c' )              1

  ( 'b',   'a' )              2

  ( 'c',   'b' )              3


first occurence  0, 1, 4, 8


reclassed list

  0 1 1 1 2 2 2 2 3 3 3 3


class     0   1   2   3   4

count    1    3   4   4   -


Now to produce the results above, you could

  • build an SQL style query using the unique combinations of inputs for each field   (ie if A =='a' and B == 'a': then...)
  • concatenate the values in each field (accounting for differences in data types), get the unique combinations

These can be determined using:

  • built in tools in arcmap ( field calculator, the Calculate Field, Frequency and Summarize tools).
  • scripting, using python with searchcursors or arcobjects.  You could even make a fancy interface to collect and present the results.

You can even produce graphs.


So... how was it done?  ... it is in the attachment.


Join the cause... frequently used tools should be part of the standard arsenal.