how to extract 1x1 array slice as matrix in R?

Question

I am working with 3D arrays. A function takes a 2D array slice (matrix) from the user and visualizes it, using row and column names (the corresponding dimnames of the array

Answer 1

The drop parameter of [ is all-or-nothing, but the abind package has an adrop function which will let you choose which dimension you want to drop:

abind::adrop(a, drop = 3)
##    B
## A   b
##   a 1