Message-ID: <A39FF7B7-C0DC-4646-9C23-722D8971E4FD@gmail.com>
Date: 2011-07-23T12:03:45Z
From: Peter Dalgaard
Subject: sum part of a vector
In-Reply-To: <2380ADA2-92B1-4699-9FA9-C7132FF3F54B@gmail.com>
On Jul 23, 2011, at 13:11 , Simon Kiss wrote:
> Dear colleagues, I have a data set that looks roughly like this;
> mydat<-data.frame(state=c(rep("Alabama", 5), rep("Delaware", 5), rep("California", 5)), news=runif(15, min=0, max=8), cum.news=rep(0, 15))
>
> For each state, I'd like to cumulatively sum the value of "news" and make that put that value in cum.news.
Like this?
> mydat <- within(mydat, cum.news <- ave(news, state, FUN=cumsum))
> mydat
state news cum.news
1 Alabama 7.9914863 7.991486
2 Alabama 7.3751514 15.366638
3 Alabama 3.4894295 18.856067
4 Alabama 3.1543811 22.010448
5 Alabama 7.9720879 29.982536
6 Delaware 2.3904745 2.390475
7 Delaware 5.5532841 7.943759
8 Delaware 5.4182249 13.361984
9 Delaware 4.6554645 18.017448
10 Delaware 3.1289714 21.146419
11 California 7.9450424 7.945042
12 California 2.0142029 9.959245
13 California 7.9735398 17.932785
14 California 1.0972878 19.030073
15 California 0.7215365 19.751609
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
"D?den skal tape!" --- Nordahl Grieg