Re: st: problems with using preserve in looping

[ken first <kenscholar2008@gmail.com>]

thanks...however i am using a common (not gen) that can not combine with by.

On 24 May 2013 16:12, William Buchanan <william@williambuchanan.net> wrote:
> What about:
>
> bys year: g B=A*matrix if inrange(year,1991,2011)
>
>
>
> Sent from my iPhone
>
> On May 24, 2013, at 10:55, ken first <kenscholar2008@gmail.com> wrote:
>
>> Dear stata users,
>>
>> I have two questions here and i hope someone can help.
>>
>> 1. I am wondering if someone knows about this strange thing with the
>> looping command. I used the below. sometimes it works and everything
>> runs smoothly and sometimes i get an error message. Does anyone know
>> what i did wrong here?
>>
>> first i have
>>
>> predict A, e
>>
>> then
>>
>> forvalue year = 1991/2011 {
>> preserve
>> keep if  year==`year'
>> gen B=A*matrix
>> restore
>> }
>>
>> already preserved
>> r(621);
>>
>>
>>
>> 2. I need to use the below as there is a matrix that wont work if i
>> simply use if year==`year', but i would like to keep the results I
>> generated after everything has been restored. does anyone know what to
>> do?
>>
>>
>> first i have
>>
>> predict A, e
>>
>> then
>>
>> forvalue year = 1991/2009 {
>> preserve
>> keep if  year==`year'
>> gen A=B*matrix   * i would like to keep the result here as a separate variable.
>> restore
>> }
>>
>> Many thanks
>>
>> Ken
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