sub setting a data frame with binomial responses

mydata <- structure(list(n = c(5, 5, 5, 5), x1 = c(2, 3, 1, 3), 

mydata

idx <- sapply(mydata[,-1], function(x) all(x %in% c(0, 5)))
idx <- c(TRUE, !idx) # add TRUE to include the first column
mydata[, idx]

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of john.james
Sent: Wednesday, August 01, 2012 10:19 AM
To: r-help at r-project.org
Subject: [R] sub setting a data frame with binomial responses

Hi everyone,
Let me have a dataframe named ?mydata? and created as below,
*> n=c(5,5,5,5) #number of trils

x1=c(2,3,1,3) ) #number of successes
x2=c(5,5,5,5) #number of successes
x3=c(0,0,0,0) #number of successes
x4=c(5,0,5,0) #number of successes
mydata=data.frame(n,x1,x2,x3,x4)
mydata*

  n x1 x2 x3 x4
1 5  2  5  0  5
2 5  3  5  0  0
3 5  1  5  0  5
4 5  3  5  0  0
But for my modeling purposes(binomial), I cannot have a dataframe which
has
all success columns, all failure columns or only the success and
failure
columns.
That is I need to delete x2, x3 and x4 from my data.frame
I can delete x2 and x3 as follows
*mydata = t(subset(t(mydata), rowSums(t(mydata)) > 0))
mydata = t(subset(t(mydata), rowSums(t(sim.data)) < 20)) #where 20=4*5*

How can I subset my data by removing x4, which contains either number
trials
or zeros as elements?
Can I give a single logical condition in the subset code to skip all
such
rows(i.e. skipping x2,x3, and x4 at once)?

*** I am doing this for a very large dataframe(1000s of columns as
responses) in a simulation study, but here I explained with a simple
case.

Thank you for your kindness!




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