Convert a matrix to long format using row names and column names.
shape_mat_long(x, unique_pairs = FALSE, na_remove = FALSE)
A data frame with the columns 'row', 'column' (indicating combinations), and 'value'
Matrix to convert to long format.
Whether only unique combinations should be included in the output (for symmetric matrices).
Logical indicating if NAs should be excluded (removes NaNs too).