在小提琴图上绘制群图会更改 ylim 并截断小提琴

import seaborn as sns
import numpy as np  # for sample data
import pandas as pd

# sample data
np.random.seed(365)
rows = 60
data1 = {'Type 1': ['a'] * rows,
         'Total': np.random.normal(loc=25, scale=3, size=rows)}
data2 = {'Type 1': ['b'] * rows,
         'Total': np.random.normal(loc=60, scale=7, size=rows)}
df = pd.concat([pd.DataFrame(d) for d in [data1, data2]], ignore_index=True)

# plot
plt.figure(figsize=(5, 4))
sns.violinplot(x='Type 1', y= 'Total', data=df, inner=None)
sns.swarmplot(x='Type 1', y= 'Total', data=df, color='#000000', size=3)

与没有的情节相比swarmplot

显示如上图，如何更改显示范围？

我试过了改变figsize https://i.stack.imgur.com/6D8ON.png. 我没有遇到这个问题，直到我重叠swarmplot到violetplot.

df

  Type 1      Total
0      a  25.503763
1      a  26.570516
2      a  27.452127
3      a  30.111537
4      a  18.559157
...
115      b  67.389032
116      b  67.337122
117      b  59.193256
118      b  56.356515
119      b  57.353019

• When adding sns.swarmplot, or a sns.stripplot, to sns.violinplot, the limits of the y-axis are changed.
  • 使用这两种方法都会发生这种情况显式“轴”接口 https://matplotlib.org/stable/users/explain/api_interfaces.html#the-explicit-axes-interface, and 隐式“pyplot”接口 https://matplotlib.org/stable/users/explain/api_interfaces.html#the-implicit-pyplot-interface，如图所示plot https://i.stack.imgur.com/oJSwd.png.
  • Using sns.catplot with kind='violin', and .map_dataframe with sns.swarmplot也产生同样的问题，如此所示plot https://i.stack.imgur.com/maDK2.png.
  • 如果绘图，则不会发生这种情况sns.swarmplot on sns.boxplot，如图所示plot https://i.stack.imgur.com/J6c6g.png.
• 测试于python 3.11.2, matplotlib 3.7.1, seaborn 0.12.2

import seaborn as sns
import matplotlib.pyplot as plt

# sample data
df = sns.load_dataset('geyser')

# plot
sns.violinplot(data=df, x='kind', y='duration', inner=None)
print('ylim with 1 plot', plt.ylim())
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3)
print('ylim with both plots', plt.ylim())

ylim with 1 plot (1.079871611291212, 5.607761736565478)
ylim with both plots (1.425, 5.2749999999999995)

解决

• Here are three options to resolve the issue:
  1. 捕获ylim绘制后的值sns.violinplot，并设置ylim绘制后的这些值sns.swarmplot.
  2. Set ylim绘图后达到某个特定值sns.swarmplot
  3. Plot sns.swarmplot then sns.violinplot.
• To have ylim从“原点”开始，使用y_bot = 0.
• Using matplotlib.pyplot.ylim https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.ylim.html, matplotlib.axes.Axes.set_ylim https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.set_ylim.html, and matplotlib.axes.Axes.get_ylim https://matplotlib.org/stable/api/_as_gen/matplotlib.axes.Axes.get_ylim.html.

1.

sns.violinplot(data=df, x='kind', y='duration', inner=None)
y_bot, y_top = plt.ylim()
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3)
plt.ylim(y_bot, y_top)

2.

sns.violinplot(data=df, x='kind', y='duration', inner=None)
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3)
plt.ylim(1, 6)

3.

# plot
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3)
print('ylim with 1 plot', plt.ylim())
sns.violinplot(data=df, x='kind', y='duration', inner=None)
print('ylim with both plots', plt.ylim())

ylim with 1 plot (1.425, 5.2749999999999995)
ylim with both plots (1.079871611291212, 5.607761736565478)

优先使用explicit界面

• 为什么要明确？ https://matplotlib.org/stable/users/explain/api_interfaces.html#why-be-explicit

plt.figure and .add_subplot

fig = plt.figure(figsize=(8, 5))
ax = fig.add_subplot()
sns.violinplot(data=df, x='kind', y='duration', inner=None, ax=ax)
y_bot, y_top = ax.get_ylim()
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3, ax=ax)
ax.set_ylim(y_bot, y_top)

plt.subplots

fig, axes = plt.subplots(figsize=(8, 5))
sns.violinplot(data=df, x='kind', y='duration', inner=None, ax=ax)
y_bot, y_top = ax.get_ylim()
sns.swarmplot(data=df, x='kind', y='duration', color='#000000', size=3, ax=ax)
ax.set_ylim(y_bot, y_top)

df[['duration', 'kind']].head()

• 这个真实数据与OP中的随机样本类似。

   duration   kind
0     3.600   long
1     1.800  short
2     3.333   long
3     2.283  short
4     4.533   long