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AW: st: AW: alternative to forvalues combined with bysort, by


From   "Martin Weiss" <martin.weiss1@gmx.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   AW: st: AW: alternative to forvalues combined with bysort, by
Date   Mon, 28 Jun 2010 14:34:26 +0200

<> 


" By the way, your
solution "(forv i=1/`=_N'{" gets the exact same results as "quietly
forvalues i = 1/`N' {""



Again sorry, you defined a -local- up there which contained _N. But still, my line does it all in one, while you need two. 



" The easiest way would be to drop the remaining seven countries and do
all this eight times. However, I would like to find a better solution.
Maybe you have one last advice on this for me. Thanks for all of your
help again!"


This is not the easiest way, and I do not know of a single problem that requires you to -drop- outright. As I said earlier, the solution to this kind of problem is -bysort-, as described by NJC in http://www.stata-journal.com/sjpdf.html?articlenum=pr0004. Looping over all rows of the data, as in 

-forv i=1/`=_N'-

is rarely necessary in Stata. 



" In each country 10000.

--> egen tag = tag(transactionid) & inrange(eventdate, eventdate[`i']
- 365, eventdate[`i'])"


-egen, tag()- takes a -varlist-, as far as I can see from its help file, but does Stata allow you to add the "& inrange()..." part w/o error?


HTH
Martin


-----Ursprüngliche Nachricht-----
Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Kaspar Dardas
Gesendet: Montag, 28. Juni 2010 14:28
An: statalist@hsphsun2.harvard.edu
Betreff: Re: st: AW: alternative to forvalues combined with bysort, by

Hi Martin,

thanks for all the help and effort. You definitely do not have to be
sorry. Its me who doesn't understand this stuff. Well, I am still
struggling with it. I think, however, I know where the problem is but
my Stata knowledge is just too bad to solve it. By the way, your
solution "(forv i=1/`=_N'{" gets the exact same results as "quietly
forvalues i = 1/`N' {"

My actual problem is that I want to tag all "transactionsids" in ONE
country 365 days prior to the current transaction. There are about
80000 transactions. In each country 10000.

--> egen tag = tag(transactionid) & inrange(eventdate, eventdate[`i']
- 365, eventdate[`i'])

All of this works fine for one country (whenever I drop the other 7
countries). However, whenever I try to use double loop version I still
get the results for my entire datasample. Thus, (very simply speaking)
all eight countries are treated as one. I think this has something do
with

local N = _N
qui forval i = 1/`N' { (or your version forv i=1/`=_N)

the _N refers to the entire dataset but I need somehow to apply the _N
for each country separately so not for 80000 but rather for 8*10000
observations. Stata also does not allow to use

bysort location: local N = _N

The easiest way would be to drop the remaining seven countries and do
all this eight times. However, I would like to find a better solution.
Maybe you have one last advice on this for me. Thanks for all of your
help again!


Best,

Kaspar

2010/6/28 Martin Weiss <martin.weiss1@gmx.de>:
>
> <>
>
> Re your assertion that -bysort- and -forvalues- do not work together: This has never been a problem for me, since -bysort- is so incredibly useful and versatile. For an intro, see NJC`s http://www.stata-journal.com/sjpdf.html?articlenum=pr0004
>
>
>
> HTH
> Martin
>
>
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Martin Weiss
> Gesendet: Montag, 28. Juni 2010 13:19
> An: statalist@hsphsun2.harvard.edu
> Betreff: AW: st: AW: alternative to forvalues combined with bysort, by
>
>
> <>
>
> Sorry about my mistake, I never noticed you had a loop nested in there, b/c of the -quietly- command in front of it. One of the problems in your code is
>
> *************
> quietly forvalues i = 1/`N' {
> *************
>
> which should be - forv i=1/`=_N'{-
>
>
> HTH
> Martin
>
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Kaspar Dardas
> Gesendet: Montag, 28. Juni 2010 12:30
> An: statalist@hsphsun2.harvard.edu
> Betreff: Re: st: AW: alternative to forvalues combined with bysort, by
>
> Martin,
>
> thanks for the prompt reply. Nesting two forvalues loops in a similar
> fashion as my second solution which includes "foreach" ? I think you
> are referring to something that I have already tried and showed in my
> firs email, correct? Or did you mean something else? I think my first
> email might have been not very precise. Again, my first command in the
> below email should run over 8 countries. My second command is my
> (failed) approach to solve it (which I think is similar to nesting two
> forvalues loops)
>
> Best,
>
> Kaspar
>
> 2010/6/28 Martin Weiss <martin.weiss1@gmx.de>:
>>
>> <>
>>
>>
>> You may want to nest two -forvalues- loops...
>>
>>
>>
>> HTH
>> Martin
>>
>>
>> -----Ursprüngliche Nachricht-----
>> Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Kaspar Dardas
>> Gesendet: Montag, 28. Juni 2010 12:11
>> An: statalist@hsphsun2.harvard.edu
>> Betreff: st: alternative to forvalues combined with bysort, by
>>
>> Hello,
>>
>> I would like to run the below forvalues loop for several countries
>> ("locations") in one large dataset. Thus, I simply need to repeat this
>> loop for subsets in one large dataset in the same fashion as the
>> bysort: command would provide. "bysort:" , however, cannot be combined
>> with forvalues.
>>
>> local N = _N
>> gen count = .
>> qui forval i = 1/`N' {
>> egen tag = tag(transactionid) if gvkey == gvkey[`i'] &
>> inrange(eventdate, eventdate[`i'] - 365, eventdate[`i'])
>> count if tag
>> replace count = r(N) in `i'
>> drop tag
>>  }
>>
>> Therefore, I have tried a foreach loop:
>>
>> foreach x in location {
>>        gen count_all_trades = . if location == `x'
>>        quietly forvalues i = 1/`N' {
>>                egen tag = tag(transactionid) if location == `x' &
>> inrange(eventdate, eventdate[`i'] - 365, eventdate[`i'])
>>                count if tag & location == `x'
>>                replace count_all_trades = r(N) in `i' if location == `x'
>>                drop tag
>>                }
>> }
>>
>> However, this does not give me the correct solution. Is there anything
>> similar to the "bysort:" command which can be used in combination with
>> the forvalues command?
>> Again, I simply need to rerun the first command for 8 different
>> countries in one large dataset. Alliteratively, I could also split my
>> dataset into 8 subsamples and run the above code 8 times. However, I
>> would like to find a more "elegant" way to solve this problem.
>>
>> Best regards,
>>
>> Kaspar
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