具有相同'设置'的matplotlib子图

Question

I'm plotting the same data in two different formats: log scale and linear scale.

Basically I want to have exactly the same plot, but with different scales, one on the top of the other.

What I have right now is this:

import matplotlib.pyplot as plt

# These are the plot 'settings'
plt.xlabel('Size')
plt.ylabel('Time(s)');
plt.title('Matrix multiplication')

plt.xticks(xl, rotation=30, size='small')
plt.grid(True)

# Settings are ignored when using two subplots

plt.subplot(211)
plt.plot(xl, serial_full, 'r--')
plt.plot(xl, acc, 'bs')
plt.plot(xl, cublas, 'g^')

plt.subplot(212)
plt.yscale('log')
plt.plot(xl, serial_full, 'r--')
plt.plot(xl, acc, 'bs')
plt.plot(xl, cublas, 'g^')

All 'settings' before plt.subplot are ignored.

I can get this to work the way I want, but I have to duplicate all the settings after each subplot declaration.

Is there a way to do configure both subplots at once?

Answer 1

The plt.* settings usually apply to matplotlib's current plot; with plt.subplot , you're starting a new plot, hence the settings no longer apply to it. You can share labels, ticks, etc., by going through the Axes objects associated with the plots ( see examples here ), but IMHO this would be overkill here. Instead, I would propose putting the common "styling" into one function and call that per plot:

def applyPlotStyle():
    plt.xlabel('Size')
    plt.ylabel('Time(s)');
    plt.title('Matrix multiplication')

    plt.xticks(range(100), rotation=30, size='small')
    plt.grid(True)

plt.subplot(211)
applyPlotStyle()
plt.plot(xl, serial_full, 'r--')
plt.plot(xl, acc, 'bs')
plt.plot(xl, cublas, 'g^')

plt.subplot(212)
applyPlotStyle()
plt.yscale('log')
plt.plot(xl, serial_full, 'r--')
plt.plot(xl, acc, 'bs')
plt.plot(xl, cublas, 'g^')

On a side note, you could root out more duplication by extracting your plot commands into such a function:

def applyPlotStyle():
    plt.xlabel('Size')
    plt.ylabel('Time(s)');
    plt.title('Matrix multiplication')

    plt.xticks(range(100), rotation=30, size='small')
    plt.grid(True)

def plotSeries():
    applyPlotStyle()
    plt.plot(xl, serial_full, 'r--')
    plt.plot(xl, acc, 'bs')
    plt.plot(xl, cublas, 'g^')

plt.subplot(211)
plotSeries()

plt.subplot(212)
plt.yscale('log')
plotSeries()

On another side note, it might suffice to put the title at the top of the figure (instead of over each plot), eg, using suptitle . Similary, it might be sufficient for the xlabel to only appear beneath the second plot:

def applyPlotStyle():
    plt.ylabel('Time(s)');

    plt.xticks(range(100), rotation=30, size='small')
    plt.grid(True)

def plotSeries():
    applyPlotStyle()
    plt.plot(xl, serial_full, 'r--')
    plt.plot(xl, acc, 'bs')
    plt.plot(xl, cublas, 'g^')

plt.suptitle('Matrix multiplication')
plt.subplot(211)
plotSeries()

plt.subplot(212)
plt.yscale('log')
plt.xlabel('Size')
plotSeries()

plt.show()

Answer 2

Hans' answer is probably the recommended approach. But in case you still want to go about copying the axis properties to another axis, here is a method I've found:

fig = figure()
ax1 = fig.add_subplot(2,1,1)
ax1.plot([1,2,3],[4,5,6])
title('Test')
xlabel('LabelX')
ylabel('Labely')

ax2 = fig.add_subplot(2,1,2)
ax2.plot([4,5,6],[7,8,9])


for prop in ['title','xlabel','ylabel']:
    setp(ax2,prop,getp(ax1,prop))

show()
fig.show()

This lets you set a white-list for which properties to set, currently I have the title , xlabel and ylabel , but you can just use getp(ax1) to print out a list of all the available properties.

You can copy all of the properties using something like the following, but I recommend against it since some of the property settings will mess up the second plot. I've tried to use a black-list to exclude some, but you'll would need to fiddle with it to get it working:

insp = matplotlib.artist.ArtistInspector(ax1)
props = insp.properties()
for key, value in props.iteritems():
    if key not in ['position','yticklabels','xticklabels','subplotspec']:
        try:
            setp(ax2,key,value)
        except AttributeError:
            pass

(The except/pass is to skip properties which are gettable, but not settable)