regex help

[Cameron Simpson]

On 13Mar2015 12:05, Larry Martell <larry.martell at gmail.com> wrote:
>I need to remove all trailing zeros to the right of the decimal point,
>but leave one zero if it's whole number. For example, if I have this:
>
>14S,5.0000000000000000,4.56862745000000,3.7272727272727271,3.3947368421052630,5.7307692307692308,5.7547169811320753,4.9423076923076925,5.7884615384615383,5.137254901960000
>
>I want to end up with:
>
>14S,5.0,4.56862745,3.7272727272727271,3.394736842105263,5.7307692307692308,5.7547169811320753,4.9423076923076925,5.7884615384615383,5.13725490196
>
>I have a regex to remove the zeros:
>
>'0+[,$]', ''
>
>But I can't figure out how to get the 5.0000000000000000 to be 5.0.
>I've been messing with the negative lookbehind, but I haven't found
>one that works for this.

Leaving aside the suggested non-greedy match, you can rephrase this: strip 
trailing zeroes _after_ the first decimal digit. Then you can consider a number 
to be:

  digits
  point
  any digit
  other digits to be right-zero stripped

so:

  (\d+\.\d)(\d*[1-9])?0*\b

and keep .group(1) and .group(2) from the match.

Another way of considering the problem.

Or you could two step it. Strip all trailing zeroes. If the result ends in a 
dot, add a single zero.

Cheers,
Cameron Simpson <cs at zip.com.au>

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