Dear R-List,
I have a dataframe X containing factor f and numeric variable x1, x2, ... I
want to create a new dataframe (or possibly a matrix) that gives statistics
(e.g. sum) for the variables x1, x2, ... in each group defined by factor f.
What is the simplest way to do this?
I tried:
attach(X)
Z <- data.frame(f=levels(f),x1=as.vector(lapply(split(x1,f),sum)))
and stumbled on:
Error in data.frame(f = levels(f), x1 = as.vector(lapply(split(x1, f), :
arguments imply differing number of rows: 5, 1
Help is much appreciated,
Wolfgang Koller
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Wolfgang Koller, koller2 at fgr.wu-wien.ac.at
Forschungsinstitut f?r Europafragen
Wirtschaftsuniversitaet Wien
Althanstrasse 39-45, 1090 Vienna, Austria
http://fgr.wu-wien.ac.at/institut/ef/ief-home.htm
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Wolfgang Koller <koller2 at fgr.wu-wien.ac.at> writes:> Dear R-List, > > I have a dataframe X containing factor f and numeric variable x1, x2, ... I > want to create a new dataframe (or possibly a matrix) that gives statistics > (e.g. sum) for the variables x1, x2, ... in each group defined by factor f. > What is the simplest way to do this? > > I tried: > attach(X) > Z <- data.frame(f=levels(f),x1=as.vector(lapply(split(x1,f),sum))) > > and stumbled on: > Error in data.frame(f = levels(f), x1 = as.vector(lapply(split(x1, f), : > arguments imply differing number of rows: 5, 1 > > Help is much appreciated,does aggregate(X, f, sum) do what you want? -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
At 13:57 15.06.00 +0200, you wrote:>Wolfgang Koller <koller2 at fgr.wu-wien.ac.at> writes: > >> Dear R-List, >> >> I have a dataframe X containing factor f and numeric variable x1, x2, ... I >> want to create a new dataframe (or possibly a matrix) that gives statistics >> (e.g. sum) for the variables x1, x2, ... in each group defined by factor f. >> What is the simplest way to do this? >> >> I tried: >> attach(X) >> Z <- data.frame(f=levels(f),x1=as.vector(lapply(split(x1,f),sum))) >> >> and stumbled on: >> Error in data.frame(f = levels(f), x1 = as.vector(lapply(split(x1, f),:>> arguments imply differing number of rows: 5, 1 >> >> Help is much appreciated, > >does aggregate(X, f, sum) do what you want?Yes it does. I should have remembered aggregate(), of course... Nevertheless, since X contains also factors I have to select variables for which summary statistics have to be computed. So I used: Z <- data.frame(f=levels(f),x1=as.vector(tapply(x1,f,sum))) I think, in the example I tried first, based on lapply(), the problem was the conversion of a list to a vector, a problem which arises quite often. Thanks for your help, Wolfgang Koller ------------------------------------------------- Wolfgang Koller, koller2 at fgr.wu-wien.ac.at Forschungsinstitut f?r Europafragen Wirtschaftsuniversitaet Wien Althanstrasse 39-45, 1090 Vienna, Austria http://fgr.wu-wien.ac.at/institut/ef/ief-home.htm ------------------------------------------------- -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._