Re: st: calculating cumulative values of other observations

[Nick Cox <njcoxstata@gmail.com>]

Why not

bysort id activity (time): gen priorhrs = sum(time) - time

Nick



On 7 Apr 2012, at 02:29, Eric Booth <eric.a.booth@gmail.com> wrote:

> <>
>
>
> ******************!
>
> //input example data//
> clear
> inp ID    str18 date  str4 activity hours
> 1    20071230  A    10
> 1    20071122  A    11
> 2    20071120  A    5
> 3    20071210  B    6
> 3    20071111  B    24
> 3    20071130  F    20
> 3    20070511  B    49
> 4    20070611  A    50
> end
>
> //cleanup//
> g date2 = date(date, "YMD")
> format date2 %td
> sort ID activity date2
>
> //gen prior hours var//
> g priorhrs = 0
> forval n = 1/`=_N' {
> by ID activity: replace priorhrs =  ///
>    priorhrs + hours[_n-`n']  ///
>    if date2[_n]>=date2[_n-`n']
>    }
>  l
> ********************!
>
>
> - Eric
>
> __
> Eric A. Booth
> Public Policy Research Institute
> Texas A&M University
> ebooth@ppri.tamu.edu
> +979.845.6754
>
>
> On Apr 6, 2012, at 6:09 PM, KOTa wrote:
>
> > Hi all,
> >
> > i have a data looking like this:
> >
> > ID    date                activity    hours prior         result  
> > should be:
> > 1    20071230      A    10       ?    <--    11
> > 1    20071122            A    11       ?        0
> > 2    20071120            A    5       ?        0
> > 3    20071210            B    6       ?        73
> > 3    20071111            B    24       ?        49
> > 3    20071130            F    20       ?        0
> > 3    20070511            B    49       ?        0
> > 4    20070611            A    50       ?        0
> >
> > (better picture here http://gyazo.com/5dc1218534d8b185ab22989069034b8a.png 
> >  )
> >
> > i need to fill "prior" column with following:
> > - amount of hours spent on same activity by same user(ID) prior to
> > date of current activity.
> >
> > example:
> > in case of observation 4(line 4) activity is B, so prior = sum of
> > hours spent on activity B before it took place (i.e. before 20071210)
> > there are 2 such observations, one with 49 hour, another with 24.
> > Therefore, prior = 24+49=73.
> >
> >
> > any suggestions how to make this simple?
> >
> > i was thinking to use "sort" and "by:", but i can't figure out how to
> > conditionally("if")  sum up values from different observations into
> > "prior" var
> > its not a first time i encounter similar problem and always took some
> > way around, but this time i decided to ask, maybe there is proper,
> > simple way to do this
> >
> > thank you in advance
> >
> > K.
> > *
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>
>
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