Odp: Collapsing panel data
Hi r-help-bounces at r-project.org napsal dne 03.02.2009 09:43:04:
Dear R-helpers, I've been thinking about this for some time, maybe someone can help. I
have
a fairly large dataset with thousands of firms, call the a, b, c, etc..
such as
[,1] [,2]
[1,] "A" 0.5
[2,] "" 0.2
[3,] "" 0.3
[4,] "B" 0.1
[5,] "" 0.9
[6,] "C" 0.4
Or to put it differently two vectors such as
y <- c("A", "", "", "B", "", "C")
x <- c(0.5, 0.2, 0.3, 0.1, 0.9, 0.4)
The empty lines "" always belong to the firm above. Now I want to
collapse
the dataset so that each firm (A,B, C, etc) has one line only, using
summation.
So what I would like is
yNew <- c("A", "B", "C")
xNew <- c(1, 1, 0.4)
That is what are NA values for. There are quite useful functions for
handling them.
y <- c("A", "", "", "B", "", "C")
x <- c(0.5, 0.2, 0.3, 0.1, 0.9, 0.4)
y[y==""]<-NA
from package zoo
y.na<-na.locf(y)
tapply(x,y.na, sum)
A B C
1.0 1.0 0.4
or aggregate(...)
Regards
Petr
The problem I'm having is that each firm has a different number of
entries
for x, so some like C have just one and others have ten or more, so I
have
difficulty imagining how to use a loop in this case. I'd be greatful for any suggestions. Karina
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.