plotting multiple curves out of one numpy array

Question

I want to plot several curves out of one numpy array with one plotting object. The array has a form like:

position=np.array([[x11,x12,...,x1n],[y11,...,y1n],[x21,...,x2n],[y21,...],...])

It should do someting like the following code:

import matplotlib.pyplot as plt
import numpy as np

position=np.load("position.npy")

fig=plt.figure()
ax=fig.add_subplot(111,aspect='equal',autoscale_on=False)
p,=ax.plot(position[0],position[1],'y-',position[2],position[3],'y-',...)

but I need the last line to have a from like this:

p,=ax.plot(position)

I can't write down every position[i] in the plot command. Is there any way to do this, e.g. with a certain array shape or any additional arguments for the plot object? I need this to plot several trajectories in an animation where (xni,yni) would be the nth particle at time i.

Thanks a lot

Hammer · Accepted Answer · 2013-10-16 19:46:38Z

3

You can unpack the list into a series of arguments. If the 'y-' isn't that important to you, this will work.

p, = ax.plot(*position)

if you want to add modifiers that apply to all the elements in your list use keyword arguments

p, = ax.plot(*position, linestyle = 'dashed', color = 'yellow')

edited Oct 16, 2013 at 19:46

answered Oct 16, 2013 at 19:38

Hammer

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Comments

rtrwalker · Accepted Answer · 2013-10-17 00:36:15Z

3

The docs for matplotlib.pyplot.plot(*args, **kwargs) say If x and/or y is 2-dimensional, then the corresponding columns will be plotted so you can slice the x and y values out of the position array:

x = position[::2,:].T 
y = position[1::2,:].T
p,=ax.plot(x, y,'y-')

edited Oct 17, 2013 at 0:36

answered Oct 16, 2013 at 22:32

rtrwalker

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1 Comment

rtrwalker Over a year ago

Thanks @Hammer it does need a transpose. I've edited my answer.

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