The layout option in Plots is row-major. I mean that plot(rand(100,4), layout = (2,2)) places series 1 and 2 on the first row instead of on the first column.

Whereas (for example) reshape(1:4, 2,2) gives 1 and 2 on the first column.

Since Julia arrays are generally column major, it might be worth making layouts column major as well for consistency.