-3

I have a matrix of n*m dimension. I wanted to count the number of columns in a row which has a value greater than "X". How to do this in R? Please let me know.

satty
  • 23
  • 1
  • 1
  • 5

1 Answers1

1

You can try rowSums

 X <- 0.5
 rowSums(m1 > X)

explanation

m1 > X will create a TRUE/FALSE logical matrix. Since TRUE values are treated as 1 and FALSE values are treated as 0, rowSums(m1 > X) will give you a count for each row of the number of values in that row that is greater than X.

data

 set.seed(24)
 m1 <- matrix(rnorm(5*10), ncol=5)
Community
  • 1
  • 1
akrun
  • 874,273
  • 37
  • 540
  • 662
  • rowSums sumup the rows and compare with the cutoff value. I would like to count how many entires in a row is greater than the cutoff value. – satty Jun 22 '15 at 09:47
  • @satty That is what it does. It compares with the cutoff values to get a `TRUE/FALSE` logical matrix and we sum the `TRUE` values to get the count of values greater than cutoff values. Also, please check the code. `rowSums(m1)` and `rowSums(m1 >X)` are different – akrun Jun 22 '15 at 09:57