Warn or forbit left multiplication about affine HOT 6 CLOSED

@Juanlu001 I agree, but this had better be for a 3.0 release (which I'll be happy to see).

from affine.

I'm not sure it is related, but I was surprised to see the following behavior:

a = Affine(1, 0, 10, 0, -1, 20)

a * Affine.scale(2)
# Affine(2.0, 0.0, 10.0,
#        0.0, -2.0, 20.0)

Affine.scale(2) * a
# Affine(2.0, 0.0, 20.0,
#        0.0, -2.0, 40.0)

from affine.

@davidbrochart matrix multiplication is not generally commutative – we can't switch the order and expect the same results.

from affine.

Then I'm not using it right - I just wanted to cut the resolution by half.

from affine.

@davidbrochart increase the pixel size by 2 while preserving the origin? In that case to do it with matrix multiplication you need to translate to (0, 0), scale, and then translate back. It's probably easier to modify the matrix elements directly.

from affine.

Thanks!

from affine.