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Re: st: Extracting substrings from variables.

From   Nick Cox <>
Subject   Re: st: Extracting substrings from variables.
Date   Fri, 25 May 2012 13:22:32 +0100

I agree with that.

I had a lot of fun working with a question posed by Tony Lachenbruch:
how to handle Roman numerals in Stata.
You could get so far with a quick and dirty approach, but doing it
properly meant grasping the nettle, biting the bullet and taking the
medicine, otherwise known as regex. The story is at

See also -moss- (SSC, Robert Picard and myself) for one convenient
wrapper for some regex problems.


On Fri, May 25, 2012 at 1:14 PM, Brendan Halpin <> wrote:
> On Fri, May 25 2012, Nick Cox wrote:
>> It's a motto of mine always to try something simpler before I try
>> regex machinery. (Nothing against regex, just a preference to use
>> something simpler when that suffices; and I've seen so many struggling
>> with regex that this preference is supported. It's also true that you
>> won't learn regex without trying it.)
> The late Eric Naggum used to say "if you think a regexp is the solution
> to your problem, you have two problems", but under certain circumstances
> regexps are expressive, and readable once you know the syntax. They're
> also portable to other contexts.
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