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 FileMaker Pro Custom Functions

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ShannonEntropy ( text )

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  Average rating: 4.0  (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.

Click here to copy To Clip Manager if you have myFMbutler's Clip Manager installed


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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