Y-axis reversed when using PyPlot.ylim

New to Julia
1

Y axis of pyplot turns upside down when using pyplot.ylim.
Is this an expected behavior of PyPlot.jl?

By the way, are the indices of images/matrixes passed to PyPlot.jl converted to 0-origin?

Thank you in advance!!

version
Julia: v1.6.0
PyPlot: v2.9.0

code

using PyPlot, Images

img = rand(20, 20)
img[5, 5] = 255
imshow(img, cmap=plt.cm.gray)
scatter(4, 4, c="r")
# scatter(5, 5, c="r") did not match the point img[5, 5] = 255
savefig("test.png")

imshow(img, cmap=plt.cm.gray)
scatter(4, 4, c="r")
ylim(0, 19)
savefig("test2.png")

output image

  1. test.png
    test

  2. test2.png
    test2

2

imshow has the y-axis order reversed compared to other 2-D plots like contourf or pcolor and ylim takes the lower and upper limit as inputs. What you want is ylim(19,0). Like this the same order is kept and you can define limits.

3

Thank you.
I didn’t know this specification at all.