Phil: thank you very much, that's exactly what I was looking for! Why I
couldn't have figured that out from the doc for myself is another
question:-)
-Jim
-----Original Message-----
From: Phil Spector [mailto:spector at stat.berkeley.edu]
Sent: 2009, April, 15 1:21 PM
To: Lane, Jim
Subject: Re: [R] How to apply a function to all combinations of the
values of 2 or more variables?
by(mf,list(mf$centre,mf$complex),summary)
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spector at stat.berkeley.edu
On Wed, 15 Apr 2009, Lane, Jim wrote:
Hi, All Forgive me if this is a stupid newbie question. I'm having no luck googling an answer to this, probably because I don't know the right R terminology to frame my question. I want to know how to run an R function on each combination of the values of 2 or more variables. In SAS-speak this is multiple "BY variables" or "CLASS variables". In R I've figured out how to do what I want with one by value. by(mf,mf$centre,summary) Centre is one of the columns in the data frame "mf" which looks like this: names(mf) [1] "centre" "complex" "appl" "pool" "month" "alloc_gb" I'd like to analyze, for example, by complex within centre. This has a
manageable number of combinations:
table(mf$centre,mf$complex)
A B C D E F G H
I J K L
B 0 0 0 0 0 0 0 0 0
0 0 60574 0
G 44 209 0 94613 0 156 0 2541 0
748 0 0 215511
O 0 0 0 0 0 0 3446 0 676
0 84400 0 0
Q 0 0 298 0 66277 0 0 0 0
0 0 0 0
In SAS what I'm after is something like:
Proc summary nway;
class centre complex;
var alloc_gb;
output out=s sum=;
run;
How do I get something similar in R?
Jim Lane
Capacity Planner
RBC Financial Group
315 Front St W
6th Floor - H14
Toronto, Ontario CANADA
M5V 3A4
416-348-6024
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