Re: st: Fwd: Fastest way to identify values that start and end with a 9?

[Daniel Feenberg <feenberg@nber.org>]

On Thu, 3 Oct 2013, Evan DeFilippis wrote:

> Values in my data set contain different numerical representations for
> "Don't Know" and "Refusal"
>
> A "Don't Know" will always start and end with a '9', but there can be
> as many '9's in between as possible, up to the maximum length of a
> string (244).
>
> A "Refusal" will always start with a '9' and end with an '8', and
> there can be as many '9's' in between as possible, up to the maximum
> length of a string (244).
>
> The data set contains strings, integers, bytes, etc..
>
> I want to be able to convert the numerical representations of 'Don't
> Know' and 'Refusal's' into DK and REF, respectively.
>
> My current strategy for doing this looks like so:
>
> quietly tostring _all, replace
> ds, has(type string)
> di "`r(varlist)'"
> unab string_vars : `r(varlist)'
> foreach j in `string_vars'  {
>  quietly replace `j'= regexr(`j', "^[9]*[9]$","DK")
>  quietly replace `j' = regexr(`j', "^[9]*[8]$", "REF")
> }
>
> However, this is slow because it converts the entire data set into
> strings, which takes about 5 minutes, and then it has to do has(type
> string) in order to get r(varlist) to iterate over all those strings
> which takes about 4 minutes.
>
> Is there a faster way to do this that perhaps does not involve
> converting everything to strings?

If you wish to end up with "DK" and "REF" as values, doesn't that make
5 minutes for conversion to strings inevitable?

dan feenberg

> Paul
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