Re: st: looping over parallel lists - is there a alternative to "for"?

["Michael Blasnik" <michael.blasnik@verizon.net>]

"Phil Schumm" <pschumm@uchicago.edu> wrote:
<snip>
>  As we all know, -foreach- cannot be used with  multiple items.  Nested 
> (macro) lists, however, are possible in Stata  by using compound quotes. 
> For example:
>
>
> loc mylist `" "1 a I" "2 b III" "3 c III" "'
> foreach element of loc mylist {
>     di "`: word 1 of `element'' `:word 2 of `element'' `:word 3 of 
> `element''"
> }
>
> will produce exactly the same output as the Python code above.
<snip>
> Thus,  IMHO, the only problem with the Stata example above is 
> that -foreach-  cannot be used with multiple items, which is why we have 
> to use the  somewhat awkward construction involving inline expansion of 
> the  extended macro function "word # of" in the call to -display-.  I have 
> no idea how difficult it would be to extend -foreach- in this way,  nor 
> have I thought seriously about the issues involved.  As I have  just 
> shown, however, such an extension might well eliminate any  lingering 
> temptations to continue using the now deprecated -for-  command.
>
>
> -- Phil
Maybe I'm not fully understanding this, but -foreach- can be used with 
multiple items:

. foreach el in "1 a I" "2 b II" "3 c III" {
 2. di "`el'"
 3. }
1 a I
2 b II
3 c III

You could also pull apart these multiple item list elements using tokenize 
within the loop if you want.

Michael Blasnik
michael.blasnik@verizon.net 
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