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st: -tostring- updated on SSC


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: -tostring- updated on SSC
Date   Tue, 22 Jul 2003 14:39:58 +0100

Thanks to Kit Baum, -tostring- has been updated 
on SSC. Stata 8 is required. To install, use -ssc- 
as usual. 

-tostring- was originally written for Stata 6 by 
Jeremy Wernow, then of Stata Corporation, and myself, 
and published in STB-56 (with a revision in STB-57). 
That version, 1.2.3, remains available for download
by users of Stata 6 or Stata 7 in the STB archives 
on the Stata website.  

The revised version, 2.0.0, implements some overdue 
revisions to bring -tostring- into line with (my 
interpretation of) good Stata practice. 

-tostring-, as the name implies, exists to convert 
numeric variables to string. It is the inverse of 
the official Stata command -destring-. One reason 
is for using it is that you have, somehow, numeric 
variables which you realise really should be string. 
This happens more rarely than the opposite, but 
it does happen. Often users have identifiers composed 
entirely of numeric digits, but then they realise that 
these are more appropriately stored as string. Another 
use is in conjunction with Roger Newson's programs 
in which you have datasets which are really resultssets 
(so to speak), but you are producing some "results are 
like restaurants" presentation in which stars are 
attached to numbers. For such a purpose, you need 
to convert your numbers to strings before you can 
affix the decoration desired.  

In a general discussion

"On numbers and strings", Stata Journal 2(3): 314-329   
(2002) 

it was suggested that the main ways of converting back 
and forth between numbers and strings should be 
thought of in pairs, namely 

(1) brute force: functions -real()-, -string()- 

(2) handling value labels: commands -encode- 
and -decode- 

(3) correcting accidents of birth: commands 
-destring- and -tostring-. 

In the same article, it was noted that some features 
of -tostring- are, in retrospect, bad, or at least arguable,
choices, and would be withdrawn in future versions: 
being able to -decode-; being able to over-write existing 
variables without specifying -, replace-; 
and being able to ignore details (especially 
in fractional parts) without specifying a -force- option.   

Now the author is able to announce a less powerful program 
from which all this functionality has been withdrawn -- 
but with the intent of 

(1) trying to produce a command which does one thing well 

(2) making it much more difficult for users accidentally to lose 
what may be important details in their 
data sets. 

In particular, one of two options, either -generate()- or 
-replace-, must now be specified.  And if converting any numeric
variable to string would result in loss of information, 
no variable will be produced unless the -force- option is 
specified. 

Nick 
n.j.cox@durham.ac.uk 

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