以循环方式在 matplotlib 图中生成新的 plt.plot 图

Question

I am trying to plot mutliple datasets in a single plot.

when you have only a small number the usual way of doing this is:

import matplotlib.pyplot as plt
y = [1,2,3,4]
x = range(len(y))
plt.plot(x,y)
plt.show()

In my case I am trying to plot 40 different list like y. Obviously

import matplotlib.pyplot as plt
y0 = [1,2,3,4]
y1 = [1,2,3,4]
:
:
y40 = [1,2,3,4]
x = range(len(y0))
plt.plot(x,y0)
plt.plot(x,y1)
:
:
plt.plot(x,y40)
plt.show()

is a pretty idiotic way of doing this... My idea was to write a function that I can call:

import matplotlib.pyplot as plt

def plotter(y):
    x = range(len(y))
    plt.plot(x,y)
y = []
for i in range(40):
    y.append([1,2,3,4])
pl = plt.figure()    
for i in range(len(SNR)):
    plotter(y[i])

pl.show()

However this opens a plot window, but closes it immediately. What am I doing wrong ?

Answer 1

maybe try something like:

fig, ax1 = plt.subplots()    

def plotter(y):
    x = range(len(y)
    ax1.plot(y)

for i in range(len(SNR)):
    plotter(SNR[i])

plt.show()

If you wanted, you could pass an axis object into the plotter function to control how the data is plotted on the graph a bit more.

EDIT:

To answer your question about adding the axis object into the function. This would allow you to plot different sets of data on different axis. So if you had two Y axis's on the graph, you could pass in the second axis and have it plotted against the right-hand y axis. You could do that like this:

fig, ax1 = plt.subplots()
ax2 = ax1.twinx()   

def plotter(y, axis):
    x = range(len(y)
    axis.plot(y)

datasetA = [1, 2, 3, 4, 5]
datasetB = [9, 8, 7, 6, 5]

plotter(datasetA, ax1)
plotter(datasetB, ax2)

plt.show()

This would plot each of the lists of data on separate axis which you could incorporate into your plotting loop if needed.

EDIT:

To answer your question about your plots closing immediately. I'm not sure, but I think that plt.show() has a block parameter, that stops the graph from closing. I don't think plot() as one, or it may be set to false as a default. (I could be wrong about this, but I'll check it out and if there is a different reason I'll edit my answer again)