如何在 matplotlib 中绘制多个 X 或 Y 轴? [英] How do I plot multiple X or Y axes in matplotlib?
问题描述
我目前正在使用matplotlib在x轴上针对2或3个其他测量值(有时是分类的)绘制测量值.目前,我正在将x轴上的数据分组为元组,并在绘制之前对它们进行排序...结果看起来像下面的左图.我想要做的是用多个 x 轴绘制数据,如右图所示.治疗"x 轴标签的分组将锦上添花.
I'm currently using matplotlib to plot a measurement against 2 or 3 other measurements (sometimes categorical) on the x-axis. Currently, I am grouping the data on the x-axis into tuples and sorting them before plotting... the result looks something like the left image below. What I would like to do is to plot the data with multiple x-axes as you see in the right image. The grouping of the "treatment" x-axis labels would be icing on the cake.
推荐答案
首先,很酷的问题!matplotlib >= 1.0.0 绝对有可能.(新的脊椎功能允许它)
First off, cool question! It's definitely possible with matplotlib >= 1.0.0. (The new spines functionality allows it)
尽管这需要相当多的伏都教...我的例子远非完美,但希望它是有道理的:
It requires a fair bit of voodoo, though... My example is far from perfect, but hopefully it makes some sense:
import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl
def main():
#-- Generate some data ----------------------------------------------------
nx = 10
x = np.linspace(0, 2*np.pi, 10)
y = 2 * np.sin(x)
groups = [('GroupA', (x[0], x[nx//3])),
('GroupB', (x[-2*nx//3], x[2*nx//3])),
('GroupC', (x[-nx//3], x[-1]))]
#-- Plot the results ------------------------------------------------------
fig = plt.figure()
ax = fig.add_subplot(111)
# Give ourselves a bit more room at the bottom
plt.subplots_adjust(bottom=0.2)
ax.plot(x,y, 'k^')
# Drop the bottom spine by 40 pts
ax.spines['bottom'].set_position(('outward', 40))
# Make a second bottom spine in the position of the original bottom spine
make_second_bottom_spine(label='Treatment')
# Annotate the groups
for name, xspan in groups:
annotate_group(name, xspan)
plt.xlabel('Dose')
plt.ylabel('Response')
plt.title('Experimental Data')
plt.show()
def annotate_group(name, xspan, ax=None):
"""Annotates a span of the x-axis"""
def annotate(ax, name, left, right, y, pad):
arrow = ax.annotate(name,
xy=(left, y), xycoords='data',
xytext=(right, y-pad), textcoords='data',
annotation_clip=False, verticalalignment='top',
horizontalalignment='center', linespacing=2.0,
arrowprops=dict(arrowstyle='-', shrinkA=0, shrinkB=0,
connectionstyle='angle,angleB=90,angleA=0,rad=5')
)
return arrow
if ax is None:
ax = plt.gca()
ymin = ax.get_ylim()[0]
ypad = 0.01 * np.ptp(ax.get_ylim())
xcenter = np.mean(xspan)
left_arrow = annotate(ax, name, xspan[0], xcenter, ymin, ypad)
right_arrow = annotate(ax, name, xspan[1], xcenter, ymin, ypad)
return left_arrow, right_arrow
def make_second_bottom_spine(ax=None, label=None, offset=0, labeloffset=20):
"""Makes a second bottom spine"""
if ax is None:
ax = plt.gca()
second_bottom = mpl.spines.Spine(ax, 'bottom', ax.spines['bottom']._path)
second_bottom.set_position(('outward', offset))
ax.spines['second_bottom'] = second_bottom
if label is not None:
# Make a new xlabel
ax.annotate(label,
xy=(0.5, 0), xycoords='axes fraction',
xytext=(0, -labeloffset), textcoords='offset points',
verticalalignment='top', horizontalalignment='center')
if __name__ == '__main__':
main()
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