st: accessing a variable's value WRT its attached value label

[Phil Schumm <pschumm@uchicago.edu>]

Suppose I have a numeric variable y, and suppose it has an attached  
value label which maps 1 -> "yes".  Now, suppose I want to count  
those cases for which y "is" yes (I'm clearly using "is" in the loose  
sense here, but I think the meaning is clear from the context).  I  
could of course type:

count if y == 1

however if the encoding of the variable changes (i.e., if the value 1  
no longer refers to "yes"), this will (silently) no longer give me  
what I want.  Alternatively (and in many cases better), I could write:

count if y == "yes":y_label

where y_label is the name of the corresponding value label.  In this  
case, if the encoding changes I'm still ok (assuming that "yes" is  
still used in the label).  But what if the *name* of the value label  
changes?  I could do this:

count if y == "yes":`:val l y'

but that's a bit ugly.  So, my question is, is there a more readable  
alternative to the expression above?

For those interested in the use case, I am working on a large project  
involving a complicated data set and a lot of code to manage the  
data.  Right now, most variables have a dedicated value label with  
the same name as the variable itself.  However, in the future, we may  
wish to economize by replacing multiple labels that have equivalent  
definitions with a single label.  This new label will clearly have a  
different name than the previous label(s) for at least one of the  
variables involved.  What I'm trying to do is to make sure that the  
code downstream will not break if such changes are made.


-- Phil

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