Add lines to plot in pyplot

Question

I want to plot a sin-function and show it, then add a cos-function and plot again, so that the output is two plots, the first with only sin and the second with sin AND cos. But show() flushes the plot, how do I prevent the flushing?

import numpy as np
import matplotlib.pyplot as plt

f1 = lambda x: np.sin(x)
f2 = lambda x: np.cos(x)
x = np.linspace(1,7,100)
y1 = f1(x)
y2 = f2(x)

plt.plot(x,y1)
plt.show() #can I avoid flushing here?

plt.plot(x,y2)
plt.show()

I need it in a jupyter notebook.

You have two plt.show() because you want two plots right? Do they have to be in the same notebook cell? You could bypass the problem by plotting them from different cells: cell 1: plt.plot(x,y1) plt.show() cell2: plt.plot(x,y1) plt.plot(x,y2) plt.show() If you don't want two plots you have to use subplots: matplotlib.org/devdocs/api/_as_gen/… — Djib2011
– Djib2011, Commented Nov 13, 2017 at 12:54
Is the aim to have 2 figures as output or to have one figure which changes its content? — ImportanceOfBeingErnest
– ImportanceOfBeingErnest, Commented Nov 13, 2017 at 13:23

en_lorithai · Accepted Answer · 2017-11-13 13:21:27Z

1

Would recommend doing it in the Object Oriented way.

%matplotlib notebook
import numpy as np
import matplotlib.pyplot as plt
import time
f1 = lambda x: np.sin(x)
f2 = lambda x: np.cos(x)
x = np.linspace(1,7,100)
y1 = f1(x)
y2 = f2(x)

f,ax = plt.subplots() # creating the plot and saving the reference in f and ax

ax.plot(x,y1)
f.canvas.draw()
time.sleep(1) # delay for when to add the second line
ax.plot(x,y2)
f.canvas.draw()

Edit: Noticed you need it in jupyter notebook and the first solution i posted didn't work there, but the one posted now does. Use f.canvas.draw() instead of plt.show().

edited Nov 13, 2017 at 13:21

answered Nov 13, 2017 at 12:59

en_lorithai

1,29010 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

chthonicdaemon Over a year ago

Why not just f1 = np.sin?

en_lorithai Over a year ago

@chthonicdaemon Sure, but the focus of this question was the plotting part.

Colin Dickie · Accepted Answer · 2017-11-13 17:32:35Z

0

Use subplot i.e.

import numpy as np
import matplotlib.pyplot as plt

f1 = lambda x: np.sin(x)
f2 = lambda x: np.cos(x)
x = np.linspace(1,7,100)
y1 = f1(x)
y2 = f2(x)
#define 2-plots vertically, 1-plot horizontally, and select 1st plot
plt.subplot(2,1,1)
plt.plot(x,y1)

#As above but select 2nd plot
plt.subplot(2,1,2)
#plot both functions
plt.plot(x,y1)
plt.plot(x,y2)
#show only once for all plots
plt.show()

answered Nov 13, 2017 at 17:32

Colin Dickie

9104 silver badges9 bronze badges

Collectives™ on Stack Overflow

Add lines to plot in pyplot

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related