Thanks for your help. Finally, I got it.
From: Dennis Murphy [mailto:djmu...@gmail.com]
Sent: Friday, February 05, 2010 12:20 PM
To: Fang (Betty) Yang
Cc: r-help@r-project.org
Subject: Re: [R] sum a particular column by group
Hi:
This is not an elegant solution by any means, but it gets what you
want...using
the data frame from your bootstrap sample,
# All combinations of the three factors
xx - with(beds, expand.grid(Region = levels(Region), Gender =
levels(Gender),
Agegr = levels(Agegr)) )
dim(xx)
[1] 12 3# differs from the 16, but bootstrapping
probably explains it...
# One way to get a summary (there are others...)
library(plyr)
yy - ddply(beds, .(Region, Gender, Agegr), summarise, Nvisits =
sum(nvisits))
res - merge(xx, yy, all.x = TRUE)
res - within(res, Nvisits[is.na(Nvisits)] - 0)
res
Region Gender Agegr Nvisits
1 O F 55--59 5
2 O F 60--64 0
3 O M 55--59 0
4 O M 60--64 0
5 S F 55--59 0
6 S F 60--64 0
7 S M 55--59 0
8 S M 60--64 6
9 W F 55--59 0
10 W F 60--64 0
11 W M 55--59 0
12 W M 60--64 2
HTH,
Dennis
On Fri, Feb 5, 2010 at 9:20 AM, Fang (Betty) Yang fang.y...@ualberta.ca
wrote:
Dear all,
I have a table like this:
eds
R.ID Region Gender Agegr Time nvisits
11 A F 60--64 1:00 1
22 OF 55--591:20 1
33 OF 55--59 3:45 3
44 SM 60--641:10 3
55 W F 55--59 12:30 1
66 W M 60--64 8:00 2
I got a bootstrap sample using the following code:
r-sample(eds[,1],replace=TRUE)
r
[1] 2 4 3 2 6 4
beds-eds[r,]
beds
R.ID Region Gender Agegr Time nvisits
2 2 O F 55--59 1:20 1
4 4 S M60--64 1:10 3
3 3 O F 55--59 3:45 3
2.12 O F 55--59 1:20 1
6 6 WM 60--64 8:00 2
4.14 SM 60--64 1:10 3
I want to sum the last column by columns 2,3,and 4(including 0 in some
group). I tried the following codes:
#1 : only get the freq, not the sum of the last column.
table-as.data.frame(with(beds,table(beds[,2],beds[,3],beds[,4])))
table
Var1 Var2 Var3 Freq
1 AF 55--590
2 OF 55--593
3 SF 55--590
4 WF 55--590
5 AM 55--590
6 OM 55--590
7 SM 55--590
8 WM 55--590
9 AF 60--640
10OF 60--640
11SF 60--640
12WF 60--640
13AM 60--640
14OM 60--640
15SM 60--642
16WM 60--641
# 2: only got the sum the last column, but miss the group with 0 counts.
aggregate(beds[,6],list(beds[,2],beds[,3],beds[,4]),sum)
Group.1 Group.2 Group.3 x
1 O F 55--59 5
2 S M 60--64 6
3 W M 60--64 2
In conclusion, the following is what I want:
Var1 Var2 Var3 Freq
1 AF 55--590
2 OF 55--595
3 SF 55--590
4 WF 55--590
5 AM 55--590
6 OM 55--590
7 SM 55--590
8 WM 55--590
9 AF 60--640
10OF 60--640
11SF 60--640
12WF 60--640
13AM 60--640
14OM 60--640
15SM 60--646
16WM 60--642
Does anyone know a code to do this or give a hint? Thank you in advance.
Betty
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