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Re: st: How to apply a command to numeric variables only


From   "Paul O'Brien" <paul.obrien@afe2.org.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: How to apply a command to numeric variables only
Date   Tue, 29 May 2012 21:58:42 +0100

These are the results:
. ds srhcareactivity1-srhcareactivity6 , has(type numeric)
srhcareact~4  srhcareact~5  srhcareact~6

. foreach var in `r(varlist)' {
  2.         decode `var', generate(string)
  3.         drop `var'
  4.         rename string `var'
  5. }
srhcareactivity4 not labeled
r(182);
===
. findname srhcareactivity1-srhcareactivity6 , type(numeric)
srhcareact~4  srhcareact~5  srhcareact~6

. foreach var in `r(varlist)' {
  2.         decode `var', generate(string)
  3.         drop `var'
  4.         rename string `var'
  5. }
srhcareactivity4 not labeled
r(182);
===
. foreach var of varlist srhcareactivity1-srhcareactivity6{
  2.     capture decode `var', generate(string)
  3.     if _rc == 0 {
  4.             drop `var'
  5.             rename string `var'
  6.      }
  7. }
unrecognized command:      capture invalid command name
r(199);
===
. ds srhcareactivity1-srhcareactivity6 , has(type numeric)
srhcareact~4  srhcareact~5  srhcareact~6

. foreach var of varlist srhcareactivity1-srhcareactivity6{
  2.         capture decode `var', generate(str)
  3.         if _rc == 0 {
  4.                 drop `var'
  5.                 rename string `var'
  6.         }
  7. }

but not decoded:
srhcareactivi~4 byte   %8.0g                  SRHCareActivity4
srhcareactivi~5 byte   %8.0g                  SRHCareActivity5
srhcareactivi~6 byte   %8.0g                  SRHCareActivity6


Paul

On 29 May 2012, at 11:00, Nick Cox wrote:

> You are reporting problems but not the exact commands you tried. I
> could try guessing what you did wrong, and whether it is my fault or
> yours, but it is really is much better if you show your code.
> 
> Nick
> 
> On Tue, May 29, 2012 at 10:55 AM, paul o'brien <paul.obrien@afe2.org.uk> wrote:
>> Thanks NIck,
>> 
>> I encounter a problem with each of these suggestions:
>> 
>> With ds and findname I get: srhcareactivity4 not labeled
>> 
>> With -capture- inside the loop I get: variable string not found
>> 
>> On keeping the label I get: unrecognized command:      local invalid =
>> command name
>> 
>> Can you help?
>> 
>> Thanks for all your very useful advice on the List.
>> 
>> Paul
>> 
>> 
>> On 29/05/2012, Paul O'Brien <paul.obrien@afe2.org.uk> wrote:
>>> Thanks NIck,
>>> 
>>> I encounter a problem with each of these suggestions:
>>> 
>>> With ds and findname I get: srhcareactivity4 not labeled
>>> 
>>> With -capture- inside the loop is get: variable string not found
>>> 
>>> On keeping the label I get: unrecognized command:      local invalid command
>>> name
>>> 
>>> Is there a tweak we are missing?
>>> 
>>> Paul
>>> 
>>> On 29 May 2012, at 08:27, Nick Cox wrote:
>>> 
>>>> Similar questions arise often on this list. In your case one solution
>>>> is to -destring- the string variables before the loop, but then the
>>>> loop will convert back, so that does not appeal.
>>>> 
>>>> Another is to select numeric variables beforehand. -ds- will do this
>>>> 
>>>> ds srhcareactivity1-srhcareactivity6 , has(type numeric)
>>>> 
>>>> foreach var in `r(varlist)' {
>>>> 
>>>> -findname- (SJ) can do more than -ds- (fact) and has a better syntax
>>>> (opinion), but its use is very similar here.
>>>> 
>>>> findname srhcareactivity1-srhcareactivity6 , type(numeric)
>>>> 
>>>> foreach var in `r(varlist)' {
>>>> 
>>>> Another way is to use -capture- inside the loop.
>>>> 
>>>> foreach var of varlist srhcareactivity1-srhcareactivity6{
>>>>     capture decode `var', generate(string)
>>>>     if _rc == 0 {
>>>>             drop `var'
>>>>             rename string `var'
>>>>      }
>>>> }
>>>> 
>>>> Is it "string" a reserved word? (I am away from manuals at the
>>>> moment.) I'd use something different here, even if not.
>>>> 
>>>> Keeping the variable label can be done with extended macro functions,
>>>> mentioned frequently on this list.
>>>> 
>>>> foreach var of varlist srhcareactivity1-srhcareactivity6{
>>>>     local varlabel : variable label `var'
>>>>     capture decode `var', generate(string)
>>>>     if _rc == 0 {
>>>>             drop `var'
>>>>             rename string `var'
>>>>             label var `var `varlabel'
>>>>      }
>>>> }
>>>> 
>>>> See -help extended fcn-. Or -help macro- first.
>>>> 
>>>> Nick
>>>> 
>>>> On Tue, May 29, 2012 at 6:28 AM, Paul O'Brien <paul.obrien@afe2.org.uk>
>>>> wrote:
>>>>> I want to do a foreach command to convert numeric variables to string
>>>>> before a merge. Only some of the variables are numeric and which ones
>>>>> varies with each database.
>>>>> 
>>>>> foreach var of varlist srhcareactivity1-srhcareactivity6{
>>>>>        decode `var', generate(string)
>>>>>        drop `var'
>>>>>        rename string `var'
>>>>> }
>>>>> 
>>>>> Error message: not possible with string variable.
>>>>> 
>>>>> I have tried using capture to ignore the error.
>>>>> 
>>>>> How can I restrict the command to numeric variables only?
>>>>> 
>>>>> By the way, is there a way to keep the variable label which is lost when
>>>>> I use generate.
>>>>> 
>>>> 
>>>> *
>>>> *   For searches and help try:
>>>> *   http://www.stata.com/help.cgi?search
>>>> *   http://www.stata.com/support/statalist/faq
>>>> *   http://www.ats.ucla.edu/stat/stata/
>>> 
>>> -------------------------------
>>> Dr Paul O'Brien
>>> Raymede Clinic
>>> Westside Contraception and Sexual Health Services
>>> Central London Community Healthcare
>>> Exmoor St
>>> London
>>> W10 6DZ
>>> UK
>>> +44 (0)20 8962 4450
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>> *
>> *   For searches and help try:
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>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
> 
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
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> *   http://www.ats.ucla.edu/stat/stata/

-------------------------------
Dr Paul O'Brien
Raymede Clinic
Westside Contraception and Sexual Health Services
Central London Community Healthcare
Exmoor St
London
W10 6DZ
UK
+44 (0)20 8962 4450











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