[R] How to use tapply with more than one variables grouped

[arun]

Hi,

Suppose if you have a threshold (say >500), then:
     
dat1<-read.table(text="
                  AL  AR  CA  NY
Doug    250 250 250  NA
Jennifer  20 340 300 100
Michele  250 500 250  60
Obama    15  45 520 600
",header=TRUE,stringsAsFactors=FALSE,sep="")
 res<-unlist(lapply(split(dat1,rownames(dat1)),function(x) x[x[!is.na(x)]>500]))
 res
Obama.CA Obama.NY 
     520      600 


# And suppose the threshold is >400
res1<-unlist(lapply(split(dat1,rownames(dat1)),function(x) x[x[!is.na(x)]>400]))
 res1
#Michele.AR   Obama.CA   Obama.NY 
  #     500        520        600 

res1[grep("Obama",names(res1))] #amount received for Obama 
#Obama.CA Obama.NY 
  #   520      600 
 length(res1[grep("Obama",names(res1))])
#[1] 2
A.K.





----- Original Message -----
From: noobmin <pseudovoid at hotmail.com>
To: r-help at r-project.org
Cc: 
Sent: Tuesday, October 23, 2012 7:41 AM
Subject: Re: [R] How to use tapply with more than one variables grouped

I believe that previously could not be understood. To facilitate'll give you
an example. Assuming my table is presented below with the amount received
from each candidate for president in a particular country state.


                   AL  AR  CA  NY
Doug     250 250 250  NA
Jennifer  20 340 300 100
Michele  250 500 250  60
Obama     15  45 520 600

I would like to list the states where Obama has higher amount received (ie
in CA and NY) and also the number of states, in this case 2. How to do this?

Thanks



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