Line for the server...
This is much clearer and the story is complete now. It does not sound like a
standard task to me. I can spot a problem in
sort id year month
levelsof id,local(l)
foreach c of local l {
egen grp=group(id year)
}
You have at least two levels of id so the -foreach- would cycle at least
twice, but after the first run you already have a variable "grp". So the
second run through the loop should end with "grp already defined r(110)"?
Can you confirm that?(If you do not condition on c in the loop, what is the
loop good for anyway?)
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Richard Harvey
Sent: Tuesday, January 13, 2009 12:06 PM
To: [email protected]
Subject: Re: st: RE: loops question
hi martin,
I am not sure what you mean by this " So far, as far as I can tell,
you have only told the list half the story..."
I am sorry if i was not clear earlier. I will try to rephrase it
The following is what i have
***************************
id year month var1
1 1980 1980m1 x
1 1980 1980m2 x
.......................
1 1980 2006m12 x
1 1981 1980m1 x
1 1981 1980m1 x
........................
1 1981 2006m12 x
2 1980 1980m1 x
2 1980 1980m2 x
.......................
2 1980 2006m12 x
2 1981 1980m1 x
2 1981 1980m1 x
........................
2 1981 2006m12 x
The following is what i want
**********************
id year month var1
1 1980 1980m4 x
.......................
1 1980 1981m4 x
1 1981 1981m4 x
1 1981 1980m1 x
........................
1 1981 2006m12 x
2 1980 1980m1 x
2 1980 1980m2 x
.......................
2 1980 2006m12 x
2 1981 1980m1 x
2 1981 1980m1 x
........................
2 1981 2006m12 x
and the following is my code that attempts to achieve the above..
********start code**********
* create grp as combination of id and year
sort id year month
levelsof id,local(l)
foreach c of local l {
egen grp=group(id year)
}
* loop over the groups to keep the relevant months
levelsof grp, local(m)
foreach d of local m {
summ year if grp==`d'
local a=`r(mean)'
local b=`a'+1
di `a' " " `b'
drop if month<m(`a'm4) | month>m(`b'm4) & grp==`d'
}
*******end code************
and that gives me the following result
id year month grp
1181 1980 1981m4 1
1181 1981 1981m4 2
1181 1981 1981m5 2
1181 1981 1981m6 2
1181 1981 1981m7 2
1181 1981 1981m8 2
1181 1981 1981m9 2
1181 1981 1981m10 2
1181 1981 1981m11 2
1181 1981 1981m12 2
1181 1981 1982m1 2
1181 1981 1982m2 2
1181 1981 1982m3 2
1181 1981 1982m4 2
So it works fine for the second group but not for the first group.
I am wondering why? I hope this is much better.
rich
p.s what does Line for the server... mean???
2009/1/13 Martin Weiss <[email protected]>:
> Line for the server...
>
> " What am I doing wrong?"
>
> The answer to that depends on how the outcome of your proposed solution
> differs from what you want to achieve.
>
> HTH
> Martin
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Richard Harvey
> Sent: Tuesday, January 13, 2009 11:33 AM
> To: [email protected]
> Subject: st: loops question
>
> Hi all,
>
> I have a dataset set up as follows
>
> id year month var1
>
> 1 1980 1980m1 x
> 1 1980 1980m2 x
> .......................
> 1 1980 2006m12 x
>
> 1 1981 1980m1 x
> 1 1981 1980m1 x
> ........................
> 1 1981 2006m12 x
>
> 2 1980 1980m1 x
> 2 1980 1980m2 x
> .......................
> 2 1980 2006m12 x
>
> 2 1981 1980m1 x
> 2 1981 1980m1 x
> ........................
> 2 1981 2006m12 x
>
> for each id year combination i want to keep the months from april of
> that year to april of next year.
>
> i.e for id 1 and year 1980 combination i want to keep months from
> april 1980 to april 1981.
> again for id 1 and year 1981 combination i want to keep months from
> april 1981 to april 1982.
>
> then for,
>
> id 2 and year 1980 combination i want to keep months from april 1980
> to april 1981.
> again for id 2 and year 1981 combination i want to keep months from
> april 1981 to april 1982
>
> so the finaldataset should look like
>
> id year month var1
>
> 1 1980 1980m4 x
> .......................
> 1 1980 1981m4 x
>
> 1 1981 1981m4 x
> 1 1981 1980m1 x
> ........................
> 1 1981 2006m12 x
>
> 2 1980 1980m1 x
> 2 1980 1980m2 x
> .......................
> 2 1980 2006m12 x
>
> 2 1981 1980m1 x
> 2 1981 1980m1 x
> ........................
> 2 1981 2006m12 x
>
>
> My logic was first to create a variable grp, where grp=group(id
> year), then loop over the grps to keep the relevant months. What am i
> doing wrong?
>
> ********start code**********
>
> * create grp as combination of id and year
>
> sort id year month
> levelsof id,local(l)
> foreach c of local l {
> egen grp=group(id year)
> }
>
> * loop over the groups to keep the relevant months
>
> levelsof grp, local(m)
> foreach d of local m {
> summ year if grp==`d'
> local a=`r(mean)'
> local b=`a'+1
> di `a' " " `b'
> drop if month<m(`a'm4) | month>m(`b'm4) & grp==`d'
> }
>
> *******end code************
>
> --
> thanks for your time
> rich
> *
> * 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/
>
> *
> * 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/
>
--
thanks for your time
rich
*
* 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/
*
* 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/
