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I wish to find the maximum element-value of a matrix and it's location (in row and column id in the matrix).
I am using the following function to return the row and column of the matrix.
This seems like a bad hack -- it's the sort of thing where i'm probably missing a native method. Is there a better / more R way?
Here's my function:
matxMax <- function(mtx) { colmn <- which(mtx == max(mtx)) %/% nrow(mtx) + 1 row <- which(mtx == max(mtx)) %% nrow(mtx) return( matrix(c(row, colmn), 1)) } I use is as follows:
mm <- matrix(rnorm(100), 10, 10) maxCords <- matxMax(mm) mm[maxCords] 
230
We have made use of the max() function which is used to find the maximum element present in an object. This object can be a Vector, a list, a matrix, a data frame, etc. The “which()” function is used to get the index or position of the value which satisfies the given condition.
In case of a 2D array (matrix), you can use: [val, idx] = max(A, [], 2); The idx part will contain the column number of containing the max element of each row.
We can find the maximum value index in a dataframe using the which. max() function. “$” is used to access particular column of a dataframe.
max() in R The max() is a built-in R function that finds the maximum value of the vector or data frame. It takes the R object as an input and returns the maximum value out of it. To find the maximum value of vector elements, data frame, and columns, use the max() function.
You could do
## Some data set.seed(123) mm <- matrix(rbinom(40, 20, 0.5), 8, 5) mm # [,1] [,2] [,3] [,4] [,5] # [1,] 9 10 8 11 11 # [2,] 12 10 6 11 12 # [3,] 9 14 9 10 6 # [4,] 13 10 14 11 10 # [5,] 13 11 13 9 12 # [6,] 6 10 11 8 8 # [7,] 10 7 11 14 9 # [8,] 13 13 16 13 8 which(mm == max(mm), arr.ind = TRUE) # row col # [1,] 8 3 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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