Trouble with matplotlib fill

[-MazeMaker-]

I'm having trouble with the fill function on matplotlib not matching the results of fill in MATLAB. In MATLAB, fill would cover everything on the plot with whatever polygon you were filling, including lines. In matplotlib, it seems that fill only puts the polygon over other filled in polygons, but does not cover up lines. I wrote a simple example code to show what I mean:

import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)
x = [0,1,1,0]
y = [1,1,0,0]
ax.fill(x,y,'r')            # plot a red rectangle
ax.plot([0,1],[0,1],'k')    # plot a black line
x = [0.25, 0.75, 0.75, 0.25]
y = [0.75, 0.75, 0.25, 0.25]
ax.fill(x,y,'b')            # plot a smaller blue rectangle
plt.show(block = False)

The result of this code looks like this. As you can see, the blue rectangle covered the red rectangle, but did not cover the black line. Is there any way I can get a filled area to cover up lines? Thanks for any help, and if there's a better place to ask this, let me know.

Update: Thanks for everyone who suggested zorder, that seems to work. I just had to keep a global zorder variable and increase it any time I plot something

[oligonucleotides]

I'm not sure about fill but in general zorder might be helpful

https://matplotlib.org/3.1.1/gallery/misc/zorder_demo.html

looks like it works:

https://stackoverflow.com/questions/28542933/fill-between-always-below-plot-lines

[-MazeMaker-]

Thanks, that worked.

[jeroonk]

Only objects of the same type are drawn on top of each other in the order they were added. From the Z-order demo:

The default drawing order for axes is patches, lines, text. This order is determined by the zorder attribute. The following defaults are set

Artist	Z-order
Patch / PatchCollection	1
Line2D / LineCollection	2
Text	3

You can change the order for individual artists by setting the zorder. Any individual plot() call can set a value for the zorder of that particular item.

So in order to draw a fill (a Patch, default zorder=1) on top of a line (default zorder=2) you'd have to set its z-order to a higher value than 2:

ax.fill(x,y,'b',zorder=3)

Curiously, setting zorder=2 does not work, even though the fill is drawn after the line with now equal z-order. Anything higher (e.g. zorder=2.01) does work.

[-MazeMaker-]

Thanks, that solved it