[R] tapply & hist

[Gabor Grothendieck]

As another respondent already mentioned, Lattice is probably the way to
go on this one but if you do want to use tapply try this:

names(Pot) <- SGruppo
dummy <- tapply(Pot,SGruppo,function(x)hist(x,main=names(x)[1],xlab=NULL))


Vittorio <v.demartino2 <at> virgilio.it> writes:

: 
: I'm learning how to use tapply. 
: Now I'm having a go at the following code in which dati contains almost 600 
: lines, Pot - numeric - are the capacities of power plants and SGruppo - text 
: - the corresponding six technologies 
("CCC", "CIC","TGC", "CSC","CPC", "TE").     
: .....................................................
: 
: dati=sqlQuery(canale,"select Id,SGruppo,Classe, NGruppo,ProdNetta,Pot from 
: SintesiQuery")
: attach(dati)
: # Grouping by technology
: tapply(Pot,SGruppo,sum)
: ...................................
: # Histograms by technology
: par(mfrow=c(2,3)) 
: tapply(Pot,SGruppo,hist)
: detach(dati)
: 
: It all works great but  tapply(Pot,SGruppo,hist) produces 6 histograms with 
: the titles and the xlab labels in a generic form, something like integer[1], 
: integer[2], ....... while I'd like to have each graph indicating the 
: mentioned technologies.
: I've been trying issuing 
: tech=c("CCC", "CIC","TGC", "CSC","CPC", "TE")
: tapply(Pot,SGruppo,hist, main=tech)
: 
: but R prints in each histogram the six values in the title without cycling 
: among them.
: 
: How can I obtain what I want?
: 
: Ciao
: Vittorio