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Re: st: identification of particular string formats

From   Jamie Fagg <>
Subject   Re: st: identification of particular string formats
Date   Fri, 06 May 2011 10:23:16 +0100

Dear Nick,

Many thanks for your reply and your time. This has solved my problem and also given me some helpful avenues for further exploration.


On 05/05/2011 18:18, Nick Cox wrote:
Note for U.S. and some other readers: the reference is to British postcodes.

I'd class this problem as one of counting _distinct_ values --
although many people would say _unique_ values. There is a review at

SJ-8-4  dm0042  . . . . . . . . . . . .  Speaking Stata: Distinct observations
         (help distinct if installed)  . . . . . .  N. J. Cox and G. M. Longton
         Q4/08   SJ 8(4):557--568
         shows how to answer questions about distinct observations
         from first principles; provides a convenience command

Using the command in question

. distinct postcode if length(postcode) == 3

. distinct postcode if !strpos(postcode, " ")

are solutions. In fact -tab postcode- with the -if- conditions will
count too, although the count is returned silently in r(r).


On Thu, May 5, 2011 at 6:07 PM, Jamie Fagg<>  wrote:

Specification: Stata version 11.1, Windows XP

I have a list of postcodes. I'd like to be able to count ones which have a
certain format. For example, from the following list, I'd like to know that
there are 2 postcodes with only 3 characters,
and 2 which have no central blank. A search of the archives hasn't helped,
mainly because I feel I'm not searching correctly.

My question is therefore, for this specific example, how would I count and
list the postcodes in question.

B30 1AH
B30 1NH
B30 1XB
B31 2QH
B31 5AX
B32 1NL
B32 1PL

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