Matplotlib：希望每行有不同的图

Question

I want go through a list composed of lists of floats, and create a different plot for each of these sublists, where the list is the y values and the same x values are used in each figure. Each figure should then be saved to my computer.

I'm using matplotlib and getting figures saved--but each subsequent figure has still has the data for the sublist(s) that was used to generate the figure before it! (eg, my 50th figure has 50 lines on it, but I only want 1.) How can this be fixed?

This is my code:

#list contains y values in sublists
x = 91,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] #my x values, floats, same for each plot
#names[] is defined earlier, is a list of desired figure names


import matplotlib.pyplot as plt
g = 0
for sublist in list:
    y = sublist
    plt.plot(x,y)
    plt.title(names[g])
    g = g + 1
    plt.savefig(genes[g-1])

Thanks in advance!

Answer 1

Your plt.plot creates a figure and axes the first time it is run. Every time after that you add a new line into the figure.

There are different ways to handle the situation. You may, eg, create and close the figure every time:

for sublist in list:
    y = sublist
    fig = plt.figure()
    plt.plot(x,y)
    plt.title(names[g])
    g = g + 1
    plt.savefig(genes[g-1])
    plt.close(fig)

This is a bit slow, even though it may not be a problem with only few dozen plots.

Or then you may only change the Y data for each image:

# create the first image as a template
l = plt.plot(x, list[0])
for sublist in list:
    l.set_ydata(sublist)
    plt.title(names[g])
    g = g + 1
    plt.savefig(genes[g-1])

In this case you only change the Y data on each round.

BTW, there are at least the following things I'd change in the code:

• move to object-oriented way of using matplotlib
• change the name list to something els ( list is highly reserved)
• there are better ways to handle g (the counter)

You might benefit from showing your code at http://codereview.stackexchange.com . There you might get a lot of valuable advice!