I am plotting two similar trajectories in matplotlib and I'd like to plot each of the lines with partial transparency so that the red (plotted second) doesn't obscure the blue.
EDIT: Here's the image with transparent lines.
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3 Answers
Plain and simple:
plt.plot(x, y, 'r-', alpha=0.7)
(I know I add nothing new, but the straightforward answer should be visible).
answered Mar 14, 2014 at 18:24
Davoud Taghawi-Nejad
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2 Comments
Alex Spurling
I can't see where the alpha parameter is documented. Could you update the answer to include where this is documented?
WaterGenie
After I plotted all the lines, I was able to set the transparency of all of them as follows:
for l in fig_field.gca().lines:
l.set_alpha(.7)
EDIT: please see Joe's answer in the comments.
4 Comments
Joe Kington
All of the maplotlib plotting functions take an alpha parameter directly. You can just do
plt.plot(x, y, 'r-', alpha=0.7).
Sven Marnach
I would be glad to see the updated picture -- could you add it to this answer please?
naught101
@JoeKington: that seems to composit the lines before applying the transparency. Is there a way to do it the other way around, so that the transparent lines add together to get darker?
Josiah Yoder
This is useful if you want to update the alpha after drawing -- e.g. when making some sort of animation.
It really depends on what functions you're using to plot the lines, but try see if the on you're using takes an alpha value and set it to something like 0.5. If that doesn't work, try get the line objects and set their alpha values directly.
1 Comment
U3.1415926
The comment by @joe-kington says all the matplotlib functions take an alpha parameter, is your answer needing a correction or his comment?