Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: Loop year variable
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: Loop year variable
Date
Sun, 21 Oct 2012 23:23:21 +0100
See for technique here
FAQ . . . . . . . . . . . . . . . . . . . . . . . Replacing missing values
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
2/03 How can I replace missing values with previous or
following nonmissing values?
http://www.stata.com/support/faqs/data/missing.html
bysort iso_o iso_d (year) : gen datewon = year if !missing(FT_A, FT_B)
& FT_A > FT_B
by iso_o iso_d : replace datewon = datewon[_n-1] if missing(datewon)
gen yrs_won = date - datewon
Nick
On Sun, Oct 21, 2012 at 10:37 PM, emanuele mazzini
<[email protected]> wrote:
> Ok, let's ignore this additional issue for the moment. I can be
> clearer I guess with the following example:
>
> +---------------------------------------------------------------------+
> | year iso_o iso_d team_A team_B FT_A FT_B date_won |
> |---------------------------------------------------------------------|
> 1. | 1982 ITA DEU Italy Germany FR 3 1 1982 |
> 2. | 1983 ITA DEU . . . |
> 3. | 1984 ITA DEU . . . |
> 4. | 1985 ITA DEU . . . |
> 5. | 1986 ITA DEU . . . |
> |---------------------------------------------------------------------|
> 6. | 1987 ITA DEU . . . |
> 7. | 1988 ITA DEU . . . |
> 8. | 1989 ITA DEU . . . |
> 9. | 1990 ITA DEU . . . |
> 10. | 1991 ITA DEU . . . |
> |---------------------------------------------------------------------|
> 11. | 1992 ITA DEU . . . |
> 12. | 1993 ITA DEU . . . |
> 13. | 1994 ITA DEU . . . |
> 14. | 1995 ITA DEU . . . |
> +---------------------------------------------------------------------+
>
> As you can see, the variable date_won is =1982 only for the year in
> which the match was played. Now, I would like to generate a new
> variable that would tell me how many years have gone by since Italy's
> last won (e.g, =0 for 1982, =1 for 1983, =2 for 1984, etc.).
> As I said, I tried with: gen yrs_won=year-date_won but this is the result:
>
> +---------+
> | yrs_won |
> |---------|
> 1. | 0 |
> 2. | . |
> 3. | . |
> 4. | . |
> 5. | . |
> |---------|
> 6. | . |
> 7. | . |
> 8. | . |
> 9. | . |
> 10. | . |
> |---------|
> 11. | . |
> 12. | . |
> 13. | . |
> 14. | . |
> +---------+
>
> As you can see, such command doesn't produce the expected result. That
> explains why I was looking for a way to expand the value of date_won
> for all cells. I thought that was the reason for the command not to
> work. Do you have any suggestion for overcoming my problem?
>
> Thank you in advance,
>
> Regards,
>
> E.M.
>
>
>
>
> 2012/10/21 Nick Cox <[email protected]>:
>> I gathered from your original posting that you had yearly data. I
>> understand that matches may be more frequent than yearly, but I can't
>> advise further without seeing what your data look like as the trade
>> data and match data are not obviously compatible.
>>
>> Nick
>>
>> On Sun, Oct 21, 2012 at 1:00 PM, emanuele mazzini
>> <[email protected]> wrote:
>>> Dear Mr Cox,
>>>
>>> thank you for your reply. The point, however, is that I cannot declare
>>> my dataset to be time-series (how would like but I cannot) due to the
>>> fact that some matches may take place once, twice or even more times
>>> in the same year. That is why I was looking form a manual command. I
>>> may better handle this first? And how can I do that in your opinion?
2012/10/21 Nick Cox <[email protected]>:
>>>> This should yield to a treatment in terms of spells in the sense of
>>>> -tsspell- (SSC) and of
>>>>
>>>> SJ-7-2 dm0029 . . . . . . . . . . . . . . Speaking Stata: Identifying spells
>>>> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
>>>> Q2/07 SJ 7(2):249--265 (no commands)
>>>> shows how to handle spells with complete control over
>>>> spell specification
>>>>
>>>> Look at -tsspell- first; it is self-contained. That is, your panels
>>>> are defined by country pairs (dyads) and the start of a spell is
>>>> defined by a match taking place (or a particular result; I don't
>>>> follow exactly what you want, e.g what about draws?). Then a variable
>>>> defined by -tsspell- gives you sequence in spell. You may need to
>>>> subtract 1.
>>>>
>>>> I don't see that loops are needed.
>>>>
>>>> Nick
>>>>
>>>> On Sun, Oct 21, 2012 at 12:07 PM, emanuele mazzini
>>>> <[email protected]> wrote:
>>>>
>>>>> I am not a new Stata user, but I have to admit I still encounter some
>>>>> problems with writing loops. A loop may not be the solution to the
>>>>> issue I am going to describe, but I thought it is tough.
>>>>>
>>>>> I do have a dataset where I have country-pair trade observations for
>>>>> years 1950-2006 as well as another information, which is football
>>>>> match result for some dyads. I therefore need to generate a variable
>>>>> that indicates how many years are passed since the last won/lost of a
>>>>> country versus another. Suppose FT_A and FT_B are the final results
>>>>> for team A and B. I thought to generate a variable as follows:
>>>>>
>>>>> gen int date_won=year if FT_A>FT_B | FT_A<FT_B
>>>>>
>>>>> in order to get a variable that is = year for every observation I have
>>>>> information about, which reports the year of the won/loss. I then
>>>>> thought to generate another variable (let's say yrs_won) to tell me
>>>>> how many years have gone by as follows:
>>>>>
>>>>> gen int yrs_won=year-date_won
>>>>>
>>>>> Unfortunately, I do not get what I want: the only value yrs_won
>>>>> assumes is 0, but for all years from 1983 until 2006 I would like it
>>>>> to be 1, 2,3 and so on.
>>>>>
>>>>> At the beginning I didn't realize the problem, now it may be occur due
>>>>> to the fact that date_won = year only for the year in which the match
>>>>> was played. I guess I need to do something such as writing a loop to
>>>>> let it spread over all cells of such variable, but I don't really know
>>>>> how to make it. Does anyone of you has any suggestion?
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/