At the risk of being wacked for asking what should be obvious.... I have a data frame with one categorical variable "CAT" and several numeric variables. I want to be able to get simple statistics on the numeric variables by level. For example, just as you can use table (CAT) to get the counts, I'd like to be able to get the means and sums by category. If someone could point me in the right direction, I'd appreciate it. I've been through the SimpleR and Using R for Data Analysis... docs and I'm still clueless. thanks for your help.
summing values by group
3 messages · Larry White, Dimitris Rizopoulos, Ignacio Colonna
you could use '?by()', e.g., dat <- data.frame(CAT=sample(letters[1:5], 100, TRUE), x=rnorm(100), y=rnorm(100), z=rnorm(100)) by(dat[sapply(dat, is.numeric)], dat$CAT, sum) by(dat[sapply(dat, is.numeric)], dat$CAT, mean) I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/336899 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat/ http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm ----- Original Message ----- From: "Larry White" <ljw1001 at gmail.com> To: <R-help at stat.math.ethz.ch> Sent: Thursday, March 24, 2005 5:12 PM Subject: [R] summing values by group
At the risk of being wacked for asking what should be obvious.... I have a data frame with one categorical variable "CAT" and several numeric variables. I want to be able to get simple statistics on the numeric variables by level. For example, just as you can use table (CAT) to get the counts, I'd like to be able to get the means and sums by category. If someone could point me in the right direction, I'd appreciate it. I've been through the SimpleR and Using R for Data Analysis... docs and I'm still clueless. thanks for your help.
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Maybe aggregate() is what you are looking for? e.g. say your data frame is called 'mydata' sum.by.CAT<-aggregate(mydata,list(CAT),sum) this will give you sums by CAT for all the variables in the data set and will yield 'NA' for any character variables you may have. Ignacio -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Larry White Sent: Thursday, March 24, 2005 10:12 AM To: R-help at stat.math.ethz.ch Subject: [R] summing values by group At the risk of being wacked for asking what should be obvious.... I have a data frame with one categorical variable "CAT" and several numeric variables. I want to be able to get simple statistics on the numeric variables by level. For example, just as you can use table (CAT) to get the counts, I'd like to be able to get the means and sums by category. If someone could point me in the right direction, I'd appreciate it. I've been through the SimpleR and Using R for Data Analysis... docs and I'm still clueless. thanks for your help. ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html