Re: st: Storing multiple values in a macro

[Keith Dear <keith.dear@anu.edu.au>]

First off, you can't really store even a single numerical value in a 
macro, except as a string representation. Macros are always strings. 
You can store a representation of several numbers by separating them 
with spaces, or indeed any character you please including none.

. loc two `=_pi' `=exp(1)'
. di "`two'"
3.141592653589793 2.718281828459045
loc two `:di %6.4f _pi'`:di %6.4f exp(1)'
. di "`two'"
3.14162.7183

Second question: if the match is 1:1 with no extra rows, and the date 
intervals don't overlap, you can sort both datasets and then simply 
stick them side by side using -merge- with no merge variables: they 
should line up properly in date order. It would be wise to check (-assert-).

Otherwise, if you data is not too large, you may be able to use 
-joinby- to build a dataset holding all pairwise combinations of the 
two datasets, then throw away the rows (n(n-1) of them) that don't match.

Keith

At 12:16 PM 3/03/2008, you wrote:

> I have a two part question.
>
> The first is, I'm wondering how to store multiple numerical values 
> in a macro.  I know how to do it with string variables, but I'm 
> stuck on numbers.
>
> The second is a more general question on a routine I'm trying to run.
> I've constructed a way to do it, but I think it must be terribly inefficient.
>
> What I'm trying to do is to merge observations based on a range 
> instead of a single value.  The match is one-to-one, but it involves 
> trying to match a single date in between a start and end date in 
> another data set.  What I did was to loop through each observation 
> in the original data set, store the values in a macro, and then 
> `use' only the single observation that corresponds to being greater 
> than the first date and less then the second.  I then tag that 
> observation with a code and append it to a new data set.  This gives 
> me a coded merge-able dataset.
>
> It seems terribly inefficient though.  I have to load one dataset, 
> clear it, load another, and then save the results to a third dataset 
> for each observation.
>
> Any ideas?
> *
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Dr Keith B.G. Dear
Senior Fellow in Biostatistics
National Centre for Epidemiology and Population Health
Australian National University
Canberra, ACT 0200, Australia
Tel: 02 612 54865, Fax: 02 612 50740
http://nceph.anu.edu.au/Staff_Students/staff_pages/dear.php
CRICOS provider #00120C

http://canberragliding.org/

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/