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st: RE: range of a stringvariable

From   "Nick Cox" <>
To   <>
Subject   st: RE: range of a stringvariable
Date   Wed, 28 Apr 2010 17:41:23 +0100

Some simpler ways of approaching this have not quite come to the surface
in this thread. 

Four key points: 

1. You are not obliged to create lots of little variables. 

2. You are not obliged to convert any bits and pieces to real unless you
genuinely want those results for other purposes. 

3. Inequalities apply to strings as well as to numbers. The order
concerned is just alphanumeric order, precisely that used by Stata to
-sort- string variables. 

4. -substr()- understands negative indexes as counted from the end of a


if inrange(substr(code, 1, 4), "E300", "E499") & substr(code, -1, 1) !=

is a complete answer to the first question. Similarly 

if substr(code,-1,1) == "A" 

is a complete answer to the second question.

It's the driest of dry reading but the functions section of the
documentation is an eye-opener in terms of the toolkit offered. 


Tomas Lind

Choose individuals based on a string variable with a range of values

I am working with ICD-10 codes (codes for different types of diseases).
codes start with a letter A - Z followed by 2 or 3 digits. In some cases
they might end with the letter A. Say that I have a dataset with 5
(id=1 to 5) with these ICD-10 codes (fake data, in reality I have
of subjects):

I460  E343  I46  C764  E438

How can I choose individuals with ICD-10 codes in the range E300 to E499
(not including codes that end up with A). What about if I want to
codes that ends with an A. (There is a convenient command for ICD-9
but not for ICD-10 codes.) 

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