findCorrelation_exact with problem in the variable selection

[igorbraga13]

Since the commit f2ad13509ba3d6ab28069840c9631a66a9e7ecc8 the function findCorrelation_exact in the row 38 are computing the wrong mean absolute correlation to the mn2. The function are calculating the mean of the matrix without the variable j instead of calculate the mean of variable j against the another variables.

Have 2 possible solutions, the first one is remove the minus sign of the j, so you will compare 2 different rows of the matrix, but the output when the verbose = TRUE prints: "Compare row i and column j with corr..." and even if the row and column are mirrored(the same) this is a incorrect text. Then we have the second option: remove the minus sign and change the j to the column position.

#before the commit
(mean(x[i, -i]) > mean(x[-j, j]) #compare the mean of two vectors
#after the commit
mn1 <- mean(x2[i,], na.rm = TRUE) #return the mean of a vector
mn2 <- mean(x2[-j,], na.rm = TRUE) #return the mean of a matrix
#possible solution 1
mn2 <- mean(x2[j,], na.rm = TRUE) #return the mean of the row 
#possible solution2
mn2 <- mean(x2[, j], na.rm = TRUE) #return the mean of the column

reprex:

require(tidyverse)
#> Carregando pacotes exigidos: tidyverse

iris <- datasets::iris
cor_mat <- as.matrix(iris[,1:4]) %>% cor()

#Finding correlation manually ----
## Example with row 3 and column 4 ----
diag(cor_mat) <- NA
cor_mat <- abs(cor_mat)
i <- 3 #simulating the i-th iteraction when i = 3
j <- 4 #simulating the j-th iteraction when j = 4

mn1 <- mean(cor_mat[i,], na.rm = TRUE)
mn2 <- mean(cor_mat[,j], na.rm = TRUE)

cat("Compare row", i, " and column ", j,
    "with corr ", round(cor_mat[i,j], 3), "\n",
    "  Means: ", round(mn1, 3), "vs", round(mn2,3))
#> Compare row 3  and column  4 with corr  0.963 
#>    Means:  0.754 vs 0.716

## Example with row 4 and column 1 ----
cor_mat[3,] <- NA #removing row 3 and column 3 to simulate the iteraction of the function, based on the previous step
cor_mat[,3] <- NA

i <- 4 #simulating the i-th iteraction when i = 3
j <- 1 #simulating the j-th iteraction when j = 4

mn1 <- mean(cor_mat[i,], na.rm = TRUE)
mn2 <- mean(cor_mat[,j], na.rm = TRUE)

cat("Compare row", i, " and column ", j,
    "with corr ", round(cor_mat[i,j], 3), "\n",
    "  Means: ", round(mn1, 3), "vs", round(mn2,3))
#> Compare row 4  and column  1 with corr  0.818 
#>    Means:  0.592 vs 0.468

#Finding correlation with findCorrelation_exact ----
iris <- datasets::iris
cor_mat <- as.matrix(iris[,1:4]) %>% cor()

vars_cor <- caret::findCorrelation(
    cor_mat,
    cutoff = 0.7,
    names = T,
    exact = T,
    verbose = T)
#> Compare row 3  and column  4 with corr  0.963 
#>   Means:  0.754 vs 0.554 so flagging column 3 
#> Compare row 4  and column  1 with corr  0.818 
#>   Means:  0.592 vs 0.417 so flagging column 4 
#> All correlations <= 0.7

^{Created on 2024-10-23 with reprex v2.1.1}

[jennybc]

I'm not sure which package this issue is meant to target, but it's not reprex. reprex is just a reporting tool, i.e. the thing that helps you render the code above nicely, for pasting into a GitHub issue. But it still needs to go into the GitHub issues of the package you're struggling with (caret maybe?). If I'm right, this is the place to go: https://github.com/topepo/caret/issues.