我正在使用“iris.csv”数据制作箱线图。我试图通过测量(即花瓣长度、花瓣宽度、萼片长度、萼片宽度)将数据分解为多个数据框,然后在 forloop 上绘制箱线图,从而添加子图。
最后,我想一次性为所有箱形图添加一个通用图例。但是,我做不到。我已经使用几个 stackoverflow 问题尝试了几个教程和方法,但我无法修复它。
这是我的代码:
import seaborn as sns
from matplotlib import pyplot
iris_data = "iris.csv"
names = ['sepal-length', 'sepal-width', 'petal-length', 'petal-width', 'class']
dataset = read_csv(iris_data, names=names)
# Reindex the dataset by species so it can be pivoted for each species
reindexed_dataset = dataset.set_index(dataset.groupby('class').cumcount())
cols_to_pivot = ['sepal-length', 'sepal-width', 'petal-length', 'petal-width']
# empty dataframe
reshaped_dataset = pd.DataFrame()
for var_name in cols_to_pivot:
pivoted_dataset = reindexed_dataset.pivot(columns='class', values=var_name).rename_axis(None,axis=1)
pivoted_dataset['measurement'] = var_name
reshaped_dataset = reshaped_dataset.append(pivoted_dataset, ignore_index=True)
## Now, lets spit the dataframe into groups by-measurements.
grouped_dfs_02 = []
for group in reshaped_dataset.groupby('measurement') :
grouped_dfs_02.append(group[1])
## make the box plot of several measured variables, compared between species
pyplot.figure(figsize=(20, 5), dpi=80)
pyplot.suptitle('Distribution of floral traits in the species of iris')
sp_name=['Iris-setosa', 'Iris-versicolor', 'Iris-virginica']
setosa = mpatches.Patch(color='red')
versi = mpatches.Patch(color='green')
virgi = mpatches.Patch(color='blue')
my_pal = {"Iris-versicolor": "g", "Iris-setosa": "r", "Iris-virginica":"b"}
plt_index = 0
# for i, df in enumerate(grouped_dfs_02):
for group_name, df in reshaped_dataset.groupby('measurement'):
axi = pyplot.subplot(1, len(grouped_dfs_02), plt_index + 1)
sp_name=['Iris-setosa', 'Iris-versicolor', 'Iris-virginica']
df_melt = df.melt('measurement', var_name='species', value_name='values')
sns.boxplot(data=df_melt, x='species', y='values', ax = axi, orient="v", palette=my_pal)
pyplot.title(group_name)
plt_index += 1
# Move the legend to an empty part of the plot
pyplot.legend(title='species', labels = sp_name,
handles=[setosa, versi, virgi], bbox_to_anchor=(19, 4),
fancybox=True, shadow=True, ncol=5)
pyplot.show()
如何在主图上、主框架之外、“主副标题”旁边添加一个通用图例?
matplotlib.pyplot.legend
和matplotlib.axes.Axes.legend
loc
bbox_to_anchor
sns.histplot
,因为 .get_legend_handles_labels()
不适用于它。seaborn
的一部分,并且它作为数据框加载。python 3.11.4
、pandas 2.0.3
、matplotlib 3.7.1
、seaborn 0.12.2
进行测试
seaborn 0.13.0
开始,在 legend=True
通话中可能需要 sns.boxplot
。import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
# load iris data
iris = sns.load_dataset("iris")
sepal_length sepal_width petal_length petal_width species
0 5.1 3.5 1.4 0.2 setosa
1 4.9 3.0 1.4 0.2 setosa
2 4.7 3.2 1.3 0.2 setosa
3 4.6 3.1 1.5 0.2 setosa
4 5.0 3.6 1.4 0.2 setosa
# create figure
fig, axes = plt.subplots(ncols=4, figsize=(20, 5), sharey=True)
# add subplots
for ax, col in zip(axes, iris.columns[:-1]):
sns.boxplot(x='species', y=col, data=iris, hue='species', dodge=False, ax=ax)
ax.get_legend().remove()
ax.set_title(col)
# add legend
handles, labels = ax.get_legend_handles_labels()
fig.legend(handles, labels, loc='upper right', ncol=3, bbox_to_anchor=(0.8, 1), frameon=False)
# add subtitle
fig.suptitle('Distribution of floral traits in the species of iris')
plt.show()
pandas.DataFrame.melt
将数据帧转换为长格式,然后使用 sns.catplot
和 kind='box'
进行绘图。dfm = iris.melt(id_vars='species', var_name='parameter', value_name='measurement', ignore_index=True)
species parameter measurement
0 setosa sepal_length 5.1
1 setosa sepal_length 4.9
2 setosa sepal_length 4.7
3 setosa sepal_length 4.6
4 setosa sepal_length 5.0
g = sns.catplot(kind='box', data=dfm, x='species', y='measurement', hue='species', col='parameter', dodge=False)
_ = g.fig.suptitle('Distribution of floral traits in the species of iris', y=1.1)
'parameter'
和 'species'
。g = sns.catplot(kind='box', data=dfm, x='parameter', y='measurement', hue='species', height=4, aspect=2)
_ = g.fig.suptitle('Distribution of floral traits in the species of iris', y=1.1)
要定位图例,设置
loc
参数(即锚点)非常重要。 (默认的 loc
是 'best'
这意味着你事先不知道它会在哪里结束)。位置从 0,0
(当前轴的左下角)到 1,1
(当前轴的左上角)进行测量。这不包括标题等的填充,因此这些值可能会超出 0, 1
范围。 “当前斧头”是最后一个被激活的斧头。
请注意,您还可以使用使用“图形”的
plt.legend
,而不是 plt.gcf().legend
(使用轴)。然后,坐标是完整图(“图”)左下角的 0,0
和右上角的 1,1
。缺点是不会为图例创建额外的空间,因此您需要手动设置顶部填充(例如plt.gcf().subplots_adjust(top=0.8)
)。缺点是您不能再使用 plt.tight_layout()
,并且将图例与轴对齐会更困难。
import seaborn as sns
from matplotlib import pyplot as plt
from matplotlib import patches as mpatches
import pandas as pd
dataset = sns.load_dataset("iris")
# Reindex the dataset by species so it can be pivoted for each species
reindexed_dataset = dataset.set_index(dataset.groupby('species').cumcount())
cols_to_pivot = ['sepal_length', 'sepal_width', 'petal_length', 'petal_width']
# empty dataframe
reshaped_dataset = pd.DataFrame()
for var_name in cols_to_pivot:
pivoted_dataset = reindexed_dataset.pivot(columns='species', values=var_name).rename_axis(None, axis=1)
pivoted_dataset['measurement'] = var_name
reshaped_dataset = reshaped_dataset.append(pivoted_dataset, ignore_index=True)
## Now, lets spit the dataframe into groups by-measurements.
grouped_dfs_02 = []
for group in reshaped_dataset.groupby('measurement'):
grouped_dfs_02.append(group[1])
## make the box plot of several measured variables, compared between species
plt.figure(figsize=(20, 5), dpi=80)
plt.suptitle('Distribution of floral traits in the species of iris')
sp_name = ['Iris-setosa', 'Iris-versicolor', 'Iris-virginica']
setosa = mpatches.Patch(color='red')
versi = mpatches.Patch(color='green')
virgi = mpatches.Patch(color='blue')
my_pal = {"versicolor": "g", "setosa": "r", "virginica": "b"}
plt_index = 0
# for i, df in enumerate(grouped_dfs_02):
for group_name, df in reshaped_dataset.groupby('measurement'):
axi = plt.subplot(1, len(grouped_dfs_02), plt_index + 1)
sp_name = ['Iris-setosa', 'Iris-versicolor', 'Iris-virginica']
df_melt = df.melt('measurement', var_name='species', value_name='values')
sns.boxplot(data=df_melt, x='species', y='values', ax=axi, orient="v", palette=my_pal)
plt.title(group_name)
plt_index += 1
# Move the legend to an empty part of the plot
plt.legend(title='species', labels=sp_name,
handles=[setosa, versi, virgi], bbox_to_anchor=(1, 1.23),
fancybox=True, shadow=True, ncol=5, loc='upper right')
plt.tight_layout()
plt.show()