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 FileMaker Pro Custom Functions

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ShannonEntropy ( text )

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  Average rating: 4.3  (3 votes)
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Richard Dyce, Dyce & Sons Ltd.

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

Sample Input:
ShannonEntropy ( "aaaaaa" )

ShannonEntropy ( "aaaabb" )

ShannonEntropy ( "abcdefg" )

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

Sample Output:




 Then copy & paste into FileMaker Advanced'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 ;-)

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

This is my Custom Function and I want to edit it


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.


Peter Gerlings, Amsterdam
January 01, 2018 11:02am

The ApplyToList() function is the standard function by Debi Fuchs:

Richard Dyce, Elgin
January 01, 2018 12:00pm


Peter Gerlings, Amsterdam
January 07, 2018 2:52pm

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Answer 2 + 3 =
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