CODEWITHSUNDEEP
pythonmatplotlib
emma
emma

Reputation: 357

deleting streamplots (matplotlib) without clearing the graph

i've always found help here until now. i've been looking for a solution of my problem very long and i might be blind by now.. i hope you can help me with this one:

i've built a python-program that plots either the direction field (quiver) or the streamplot. since there might be other data in the graph (e.g. trajectories) i can't just clear everything and replot. instead i want to delete single elements. this works perfect for everything except the streamplot.

so, the streamplot consists of lines and arrows. stored in the variable sl i can simply call sl.lines.remove() to delete the lines. this doesn't work for the arrows, though. how do i delete these?

edit: so here's a little code:

import numpy as np
import matplotlib.pyplot as pp

streamplot = None

def mySystem(z):
    x, y = z
    return y, -x


def stream():
    xmin = -10
    xmax = 10
    ymin = -10
    ymax = 10

    N = 40
    M = int(N)
    a = np.linspace(xmin,xmax,N)
    b = np.linspace(ymin,ymax,N)

    X1, Y1 = np.meshgrid(a,b)
    DX1, DY1 = mySystem([X1,Y1])

    global streamplot
    streamplot = pp.streamplot(X1, Y1, DX1, DY1, density=2, color='#b5b5b5')

def removeStream():
    global streamplot
    streamplot.lines.remove()

    #doesn't work: streamplot.arrows.remove()

stream()
removeStream()
pl.show() # arrows still here!

Upvotes: 4

Views: 1822

Answers (1)

Joe Kington
Joe Kington

Reputation: 284830

There is a workaround for PatchCollection not having a working remove method.

The arrows are added to ax.patches. Assuming you don't have any other patches in the plot (e.g. a bar plot uses patches), you can just do ax.patches = [] to remove the arrows.

Ideally, you'd get the patches from the sl.arrows PatchCollection, but it doesn't actually store a reference to the patches themselves, just their raw paths.

If you do have other patches in the plot, you could remove all instances of FancyArrowPatch instead. E.g.

keep = lambda x: not isinstance(x, mpl.patches.FancyArrowPatch)
ax.patches = [patch for patch in ax.patches if keep(patch)]

Upvotes: 2

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