To loop you can use the command -ds-:
if you want to do that to all the variables in the data set, except for
the id number, then you can say:
(1) ds idnumber, not
alternatively you can have:
(2) ds -the 100 variables-
Or if you 100 variables all start with a certain set of letters, say vars1
to vars100, you write:
ds vars*
After either (1) or (2) or (3), you can write the loop as follows:
foreach var of varlist `r(varlist)' {
COMMANDS TO BE LOOPED
}
> now suppose I had to do this operation in 100 different variabes (call
> them
> var1-var100), how can i code a simple loot to do that?
>
> i want to perform this within each variable: gen Var2=(Var1+Var1[_n-1])/2
> if mod(_n,2)==0
>
> (even _n calculations are fine...)
>
> Thanks!
>
>
>>From: Kit Baum <[email protected]>
>>Reply-To: [email protected]
>>To: [email protected]
>>Subject: st: re: averaging within a variable
>>Date: Tue, 12 Jul 2005 22:32:13 -0400
>>
>>Austin said
>>
>>g Var2=(Var1+Var1[_n-1])/2 if mod(_n,2)==0
>>
>>-----Original Message-----
>>From: kelly johnson [mailto:[email protected]]
>>Sent: Tuesday, July 12, 2005 9:51 PM
>>Hi,
>>Quick question: suppose I have a variable like this:
>>N Var1
>>1 12
>>2 45
>>3 65
>>100 15
>>How can I create a new variable whose first observation is the average of
>>Var1[1] and Var1[2], second observation is the avaerage of Var1[3] and
>>Var1[4], etc. There will be a total of 50 observations for this new
>>variable. Thanks in advance!
>>
>>Not quite. That creates the even-numbered obs. of Var2 as the desired
>>values, with the odd-numbered values equal to missing. To fix that up,
>>thanks to Bill Gould's excellent tutorial at this morning's Boston SUG
>>meeting, you may use a cute mata trick (in Stata 9, anyway):
>>
>>clear
>>set obs 100
>>g Var1=_n
>>g Var2=(Var1+Var1[_n-1])/2 if mod(_n,2)==0
>>mata:
>> v = st_data(.,"Var2",0) // grab nonmissing elements of Var2
>> null=J(50,1,.)
>> v = v\null // append 50 missings
>> st_store(.,2,v) // stuff it back in Var2
>> end
>>list
>>
>>
>>Kit Baum, Boston College Economics
>>http://ideas.repec.org/e/pba1.html
>>
>>*
>>* For searches and help try:
>>* http://www.stata.com/support/faqs/res/findit.html
>>* http://www.stata.com/support/statalist/faq
>>* http://www.ats.ucla.edu/stat/stata/
>
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> *
> * For searches and help try:
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> * http://www.stata.com/support/statalist/faq
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>
*
* For searches and help try:
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