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sub setting a data frame with binomial responses

3 messages · john.james, David L Carlson, arun kirshna [via R]

john.james
# 
Hi everyone,
Let me have a dataframe named ?mydata? and created as below,
*> n=c(5,5,5,5) #number of trils
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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David L Carlson
# 
If I understand you correctly you want to exclude columns where all successes equal trials, all successes equal 0, or successes are a mixture of trials and 0 with no in between values. You did not make it clear if the number of trials can vary, but in your example they do not. Given that all three criteria can be consolidated into a single statement:
x2 = c(5, 5, 5, 5), x3 = c(0, 0, 0, 0), x4 = c(5, 0, 5, 0)), 
  .Names = c("n", "x1", "x2", "x3", "x4"), row.names = c(NA, -4L), 
  class = "data.frame")
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
n x1
1 5  2
2 5  3
3 5  1
4 5  3

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352