Removing rows in R based on values in a single column
You could also use the subset() function.
a <- matrix(1:9, nrow=3) threshhold <- 8 subset(a, a[ , 3] < threshhold)
Same approach as @JeffAllen but in a little more detail and generalisable to a matrix of any size.
data <- rbind(c(1,2,3), c(1, 7, 4), c(4,6,7), c(3, 3, 3), c(4, 8, 6)) data [,1] [,2] [,3] [1,] 1 2 3 [2,] 1 7 4 [3,] 4 6 7 [4,] 3 3 3 [5,] 4 8 6 # # set value of x x <- 3 # # return matrix that contains only those rows where value in # the final column is greater than x. # This will scale up to a matrix of any size data[data[,ncol(data)]>x,] [,1] [,2] [,3] [1,] 1 7 4 [2,] 4 6 7 [3,] 4 8 6
m <- matrix(rnorm(9), ncol=3)m <- m[m[,3]>0,]Creates a matrix, then redefines that matrix only to include those rows in which the third column is greater than 0 (m[,3] > 0).