[R] counting the number of rows that satisfy a certain criteria

[arun]

Hi,
Try:
set.seed(42)
 X <- as.data.frame(matrix(sample(0:1, 4*50,replace=TRUE), ncol=4))
 table(X[1:2])[4]
#[1] 15

sum(rowSums(X[1:2])==2)
#[1] 15
A.K.




On Saturday, June 21, 2014 10:59 AM, Kate Ignatius <kate.ignatius at gmail.com> wrote:
I have 4 columns, and about 300K plus rows with 0s and 1s.

I'm trying to count how many rows satisfy a certain criteria... for
instance, how many rows are there that have the first column == 1 as
well as the second column == 1.

I've tried using rowSums and colSums but it keeps giving me this type of error:

Error in rowSums(X[1] == 1 & X[2] == 1) :
  'x' must be an array of at least two dimensions

Thanks in advance!

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