We agree.
Nick
[email protected]
Jeph Herrin
Yes, originally I wrote this as a wrapper for -ds-, but found I
still had to loop over the return list to check for assigned values
so bagged -ds- altogether in the end.
That said, obviously, if you don't care what the value of a
characteristic is, there is no reason to assign such values.
I have datasets that consist of dozens of linked tables containing
thousands of variables. The more information I can attach to a
variable the first time I look at it, the more I can automate
my analyses and output, which in such a situation is highly
desirable.
Nick Cox wrote:
> Note that the official Stata command -ds- already has options -has()-
> and -not()- that permit identification of variables with or without
> named characteristics (but not their contents, as here).
>
> There is much scope for different programming styles, but flagging
that
> a variable has a particular property can be done by assigning any
> non-empty text. Putting informative detail _inside_ characteristics
has
> disadvantages as well as advantages, as the programmer is
> correspondingly obliged to, or able to, look inside.
Jeph Herrin
> [email protected] wrote:
>> the following is a "dirty" but - at least for me - useful trick:
>>
>
> Several have suggested using characteristics to store this kind of
> info, and I concur. The main disadvantage of both schemes
> is that it can be difficult to figure out which variables have
> which characteristics - I wrote the program below to list variables
> that either have a certain characteristic defined, or have a
> certain value for a given characteristic. Ie,
>
> dchar, char(graph percent)
>
> will list all variables with characteristic 'graph' defined
> and equal to 'percent'; or
>
> dchar, char(graph)
>
> will simply list all variables with characteristics `graph'
> defined. The program also takes a varlist, to limit the search,
> and stores the hit list in r(varlist).
>
> hth,
> Jeph
>
>
>
> *****************************************
> * DCHAR
> * program to get list of variables with
> * certain characteristics
> *!
> *! version 1.0 27 Aug 2009
> *****************************************
>
> program define dchar, rclass
> syntax [varlist] , CHar(string)
> local char1 : word 1 of `char'
> local char2 : word 2 of `char'
> local rlist ""
> local numvars 0
> di ""
> foreach V of varlist `varlist' {
> local charlist : char `V'[]
> local found : list char1 in charlist
> if `found'>0 {
> if "`char2'"!="" {
> local charval : char `V'[`char1']
> if "`charval'"=="`char2'" {
> di in y "`V'" _col(40) in g
///
> "`char1'" _col(50) "`char2'"
> local rlist "`rlist'`V' "
> local numvars = `numvars'+1
> }
> }
> else {
> local charval : char `V'[`char1']
> di in y "`V'" _col(40) in g ///
> "`char1'" _col(50) "`charval'"
> local rlist "`rlist'`V' "
> local numvars = `numvars'+1
> }
> }
> }
> return local varlist "`rlist'"
> return scalar numvars= `numvars'
> end
> *****************************************
*
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