小提琴图 (Violin Plot) 用于显示数据分布及其概率密度。
这种图表结合了箱形图和密度图的特征，主要用来显示数据的分布形状。中间白点为中位数，中间的黑色粗条表示四分位数范围。上下贯穿小提琴图的黑线代表最小非异常值min到最大非异常值max的区间，线上下端分别代表上限和下限，超出此范围为异常数据。（或者，从黑色粗条延伸的细黑线代表 95% 置信区间）
Matplotlib库中，使用violinplot()函数来绘制小提琴图。
例子1：
import matplotlib.pyplot as plt
import numpy as np
fig, axes = plt.subplots(nrows=1, ncols=2, figsize=(9, 4))
# Fixing random state for reproducibility
np.random.seed(19680801)
# generate some random test data
all_data = [np.random.normal(0, std, 100) for std in range(6, 10)]
# plot violin plot
axes[0].violinplot(all_data,showmeans=False,showmedians=True)
axes[0].set_title('Violin plot')
# plot box plot
axes[1].boxplot(all_data)
axes[1].set_title('Box plot')
# adding horizontal grid lines
for ax in axes:
ax.yaxis.grid(True)
ax.set_xticks([y 1 for y in range(len(all_data))])
ax.set_xlabel('Four separate samples')
ax.set_ylabel('Observed values')
# add x-tick labels
plt.setp(axes, xticks=[y 1 for y in range(len(all_data))],
xticklabels=['x1', 'x2', 'x3', 'x4'])
plt.show()例子2:
"""
This example demonstrates how to fully customize violin plots.
"""
import matplotlib.pyplot as plt
import numpy as np
def adjacent_values(vals, q1, q3):
upper_adjacent_value = q3 (q3 - q1) * 1.5
upper_adjacent_value = np.clip(upper_adjacent_value, q3, vals[-1])
lower_adjacent_value = q1 - (q3 - q1) * 1.5
lower_adjacent_value = np.clip(lower_adjacent_value, vals[0], q1)
return lower_adjacent_value, upper_adjacent_value
def set_axis_style(ax, labels):
ax.get_xaxis().set_tick_params(direction='out')
ax.xaxis.set_ticks_position('bottom')
ax.set_xticks(np.arange(1, len(labels) 1))
ax.set_xticklabels(labels)
ax.set_xlim(0.25, len(labels) 0.75)
ax.set_xlabel('Sample name')
# create test data
np.random.seed(19680801)
data = [sorted(np.random.normal(0, std, 100)) for std in range(1, 5)]
fig, (ax1, ax2) = plt.subplots(nrows=1, ncols=2, figsize=(9, 4), sharey=True)
ax1.set_title('Default violin plot')
ax1.set_ylabel('Observed values')
ax1.violinplot(data)
ax2.set_title('Customized violin plot')
parts = ax2.violinplot(
data, showmeans=False, showmedians=False,
showextrema=False)
for pc in parts['bodies']:
pc.set_facecolor('#D43F3A')
pc.set_edgecolor('black')
pc.set_alpha(1)
quartile1, medians, quartile3 = np.percentile(data, [25, 50, 75], axis=1)
whiskers = np.array([
adjacent_values(sorted_array, q1, q3)
for sorted_array, q1, q3 in zip(data, quartile1, quartile3)])
whiskersMin, whiskersMax = whiskers[:, 0], whiskers[:, 1]
inds = np.arange(1, len(medians) 1)
ax2.scatter(inds, medians, marker='o', color='white', s=30, zorder=3)
ax2.vlines(inds, quartile1, quartile3, color='k', linestyle='-', lw=5)
ax2.vlines(inds, whiskersMin, whiskersMax, color='k', linestyle='-', lw=1)
# set style for the axes
labels = ['A', 'B', 'C', 'D']
for ax in [ax1, ax2]:
set_axis_style(ax, labels)
plt.subplots_adjust(bottom=0.15, wspace=0.05)
plt.show()例子3：
import random
import numpy as np
import matplotlib.pyplot as plt
# Fixing random state for reproducibility
np.random.seed(19680801)
# fake data
fs = 10 # fontsize
pos = [1, 2, 4, 5, 7, 8]
data = [np.random.normal(0, std, size=100) for std in pos]
fig, axes = plt.subplots(nrows=2, ncols=3, figsize=(6, 6))
axes[0, 0].violinplot(data, pos, points=20, widths=0.3,
showmeans=True, showextrema=True, showmedians=True)
axes[0, 0].set_xticks(pos)
axes[0, 0].set_xticklabels(["A","B","C","D","E","F"])
axes[0, 0].set_xlabel('group name')
axes[0, 0].set_title('Custom violinplot 1', fontsize=fs)
axes[0, 1].violinplot(data, pos, points=40, widths=0.5,
showmeans=True, showextrema=True, showmedians=True,
bw_method='silverman')
axes[0, 1].set_title('Custom violinplot 2', fontsize=fs)
axes[0, 2].violinplot(data, pos, points=60, widths=0.7, showmeans=True,
showextrema=True, showmedians=True, bw_method=0.5)
axes[0, 2].set_title('Custom violinplot 3', fontsize=fs)
axes[1, 0].violinplot(data, pos, points=80, vert=False, widths=0.7,
showmeans=True, showextrema=True, showmedians=True)
axes[1, 0].set_title('Custom violinplot 4', fontsize=fs)
axes[1, 1].violinplot(data, pos, points=100, vert=False, widths=0.9,
showmeans=True, showextrema=True, showmedians=True,
bw_method='silverman')
axes[1, 1].set_title('Custom violinplot 5', fontsize=fs)
axes[1, 2].violinplot(data, pos, points=200, vert=False, widths=1.1,
showmeans=True, showextrema=True, showmedians=True,
bw_method=0.5)
axes[1, 2].set_title('Custom violinplot 6', fontsize=fs)
#for ax in axes.flatten():
#ax.set_yticklabels([])
fig.suptitle("Violin Plotting Examples")
fig.subplots_adjust(hspace=0.4)
plt.show()
