CODEWITHSUNDEEP
pythonmatplotlibplot
Sibbs Gambling
Sibbs Gambling

Reputation: 20345

How to remove the previous drawing in matplotlib, Python?

I have run 3 Python scripts and each of them generated one curve in the plot.

Each curve is made up of hundreds of small line segments.

Thus, each curve is drawn by a series of plot() instead of one.

But all these plot() share the same parameters (e.g. the color, style of one curve is consistent).

Thus, I think it is still possible to easily remove all the segments drawn by particular one script.

I find that the curve generated by the most-recently-run script is erroneous. Therefore, I wish to remove it. But at the same time, I cannot afford to just close the window and redraw everything. I wish to keep all the other curves there.

How may I do that?

Updates: Plotting Codes

for i, position in enumerate(positions):
    if i == 0:
        plt.plot([0,0], [0,0], color=COLOR, label=LABEL)
    else:
        plt.plot([positions[i - 1][0], position[0]], [positions[i - 1][1], position[1]], STYLE, color=COLOR)

#plt.plot([min(np.array(positions)[:,0]), max(np.array(positions)[:,0])], [0,0], color='k', label='East') # West-East
#plt.plot([0,0], [min(np.array(positions)[:,1]), max(np.array(positions)[:,1])], color='k', label='North') # South-North

plt.gca().set_aspect('equal', adjustable='box')

plt.title('Circle Through the Lobby 3 times', fontsize=18)
plt.xlabel('x (m)', fontsize=16)
plt.ylabel('y (m)', fontsize=16)
plt.legend(loc='center left', bbox_to_anchor=(1, 0.5))
plt.draw()

Upvotes: 1

Views: 6858

Answers (1)

tacaswell
tacaswell

Reputation: 87356

I think your entire loop could be replaced by:

pos = np.vstack(positions) # turn your Nx2 nested list -> Nx2 np.ndarray
x, y = pos.T # take the transpose so 2xN then unpack into x and y
ln, = plt.plot(x, y, STYLE, color=COLOR, label=LABEL)

Note the , it is important and unpacks the list that plot returns.

If you want to remove this line, just do

ln.remove()  # remove the artist
plt.draw()   # force a re-rendering of the canvas (figure) to reflect removal

I can't tell if you use of positions[-1] is intentional or not, but if you want to force it to be periodic, do

pos = np.vstack(positions + positions[:1])

If you really want to plot each segment as a sepreate line, use LineCollection, see https://stackoverflow.com/a/17241345/380231 for an example

Upvotes: 3

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