Brian Dunning's FileMaker Custom Functions

ShannonEntropy ( text )

A function for calculating the entropy of a string - how difficult is it to encode.

  Average rating: 4.0 (3 votes) Log in to vote

Richard Dyce   Richard Dyce - Show more from this author
Dyce & Sons Ltd.

Share on Facebook Share on Twitter

  Sample input:
ShannonEntropy ( "aaaaaa" )

ShannonEntropy ( "aaaabb" )

ShannonEntropy ( "abcdefg" )

ShannonEntropy ( "This is some text. It is very long" )

  Sample output:




  Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

The Shannon Entropy is the minimal number of bits per symbol needed to encode the information in binary form. It's a good rule of thumb measure of how strong your password is ;-)



Peter Gerlings   Peter Gerlings, Amsterdam
Jan 1, 2018
This seems to reference two custom functions. I can find one by the same author on this site, but I can’t find one for “ApplyToList”. If the author sees this, please provide references to the appropriate subroutines. This would be very useful for me, but I can’t get it to work.

Richard Dyce   Richard Dyce, Dyce & Sons Ltd.
Jan 1, 2018
The ApplyToList() function is the standard function by Debi Fuchs:
Peter Gerlings   Peter Gerlings, Amsterdam
Jan 7, 2018

Log in to post comments.


Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

Support this website.

This library has been a free commmunity resource for FileMaker users and developers for 16 years. It receives no funding and has no advertisements. If it has helped you out, I'd really appreciate it if you could contribute whatever you think it's worth: