Why don't I get a matrix of colors instead of a vector?

New to Julia
1

When I create four random colors, a and b show up as a row of four swatches
But when I try to create a matrix [a;b], figuring four over and under, all I get is a vector row of eight swatches

What am I doing wrong?

a = [RGB(rand(),rand(),rand()) for x in 1:4]
b = [RGB(rand(),rand(),rand()) for x in 1:4]

[a;b]

image

2

Interesting. I also want to know, but I would’ve done

vcat(a, b)

or

transpose([a b])

or

reshape([a;b], 2, :)
3

This is a matter of Julia’s design, not a problem of colors.

julia> a = [1, 2, 3, 4]; b = [5, 6, 7, 8];

julia> [a; b]
8-element Vector{Int64}:
 1
 2
 3
 4
 5
 6
 7
 8

However, I don’t think it is useful to arrange the color swatches vertically.

1 Like
4

To get a 2-row matrix from two vectors of reals one can do: [a'; b'] for more general case you could use: permutedims([a b])

1 Like
5

Thanks. What is the apostrophe for? I haven’t seen that usage.

6

Check the help:

help?>  '
  A'
  adjoint(A)

  Lazy adjoint (conjugate transposition). Note that adjoint is applied recursively to elements.

  For number types, adjoint returns the complex conjugate, and therefore it is equivalent to the identity function for real    
  numbers.

  This operation is intended for linear algebra usage - for general data manipulation see permutedims.
1 Like