Return True Indices of a Logical Object in R Programming – which() Function
which()
function in R Language is used to return the indices of the object which return true for the logical operation passed as argument.
Syntax: which(x, arr.ind)
Parameters:
x: logical object
arr.ind: Boolean value to display indices
Example 1:
# R program to illustrate # the use of which() function # Create a matrix x < - matrix( 1 : 9 , 3 , 3 ) x # Calling which() function which(x % % 2 = = 0 , arr.ind = TRUE) |
Output:
[, 1] [, 2] [, 3] [1, ] 1 4 7 [2, ] 2 5 8 [3, ] 3 6 9 row col [1, ] 2 1 [2, ] 1 2 [3, ] 3 2 [4, ] 2 3
Here, in the above code, the which()
function returns the indices of all the even numbers present in the matrix.
Example 2:
# R program to illustrate # the use of which() function # Using predefined dataset BOD # Calling which() function which(BOD$demand = = 19 , arr.ind = TRUE) |
Output:
Time demand 1 1 8.3 2 2 10.3 3 3 19.0 4 4 16.0 5 5 15.6 6 7 19.8 [1] 3
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