heatmap permutes data

[anandijain]

[JonasIsensee]

While this may not be what you were expecting, this is correct behaviour.
matrix columns are shown along the X axis and rows along Y. (so that you can think of "indexing" as matrix[x,y,z])
Then also note that one prints matrices with mat[1,1] in the top left corner while the point (0,0) of a heatmap is in the lower left.