ecdf: 创建经验累积分布函数图表

一个方便绘制经验累积分布函数的函数。

> from mlxtend.ecdf import ecdf

概述

一个方便绘制经验累积分布函数（ECDF）并为探索性数据分析添加百分位数阈值的函数。

参考文献

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示例 1 - ECDF

from mlxtend.data import iris_data
from mlxtend.plotting import ecdf
import matplotlib.pyplot as plt

X, y = iris_data()

ax, _, _ = ecdf(x=X[:, 0], x_label='sepal length (cm)')
plt.show()

示例 2 - 多个经验累积分布函数（ECDFs）

from mlxtend.data import iris_data
from mlxtend.plotting import ecdf
import matplotlib.pyplot as plt

X, y = iris_data()

# 首次经验累积分布函数
x1 = X[:, 0]
ax, _, _ = ecdf(x1, x_label='cm')

# 第二经验累积分布函数
x2 = X[:, 1]
ax, _, _ = ecdf(x2, ax=ax)

plt.legend(['sepal length', 'sepal width'])
plt.show()

示例 3 - 带百分位数阈值的经验累积分布函数 (ECDF)

from mlxtend.data import iris_data
from mlxtend.plotting import ecdf
import matplotlib.pyplot as plt

X, y = iris_data()

ax, threshold, count = ecdf(x=X[:, 0], 
                            x_label='sepal length (cm)',
                            percentile=0.8)

plt.show()

print('Feature threshold at the 80th percentile:', threshold)
print('Number of samples below the threshold:', count)

Feature threshold at the 80th percentile: 6.5
Number of samples below the threshold: 120

API

ecdf(x, y_label='ECDF', x_label=None, ax=None, percentile=None, ecdf_color=None, ecdf_marker='o', percentile_color='black', percentile_linestyle='--')

Plots an Empirical Cumulative Distribution Function

Parameters

• x : array or list, shape=[n_samples,]

  Array-like object containing the feature values

• y_label : str (default='ECDF')

  Text label for the y-axis

• x_label : str (default=None)

  Text label for the x-axis

• ax : matplotlib.axes.Axes (default: None)

  An existing matplotlib Axes. Creates one if ax=None

• percentile : float (default=None)

  Float between 0 and 1 for plotting a percentile threshold line

• ecdf_color : matplotlib color (default=None)

  Color for the ECDF plot; uses matplotlib defaults if None

• ecdf_marker : matplotlib marker (default='o')

  Marker style for the ECDF plot

• percentile_color : matplotlib color (default='black')

  Color for the percentile threshold if percentile is not None

• percentile_linestyle : matplotlib linestyle (default='--')

  Line style for the percentile threshold if percentile is not None

Returns

• ax : matplotlib.axes.Axes object

• percentile_threshold : float

  Feature threshold at the percentile or None if percentile=None

• percentile_count : Number of if percentile is not None

  Number of samples that have a feature less or equal than the feature threshold at a percentile threshold or None if percentile=None

Examples

For usage examples, please see https://rasbt.github.io/mlxtend/user_guide/plotting/ecdf/