Python Pandas - 基于底层分类创建索引


要基于底层分类创建索引,请使用 **pandas.CategoricalIndex()** 方法。

首先,导入所需的库 −

import pandas as pd

CategoricalIndex 是基于底层分类的索引。CategoricalIndex 可以采用有限的(通常是固定的)数量的可能值。使用“categories”参数设置分类的类别。使用“ordered”参数将分类视为有序 −

catIndex = pd.CategoricalIndex(
   ["p", "q", "r", "s","p", "q", "r", "s"], ordered=True, categories=["p", "q", "r", "s"]
)

显示分类索引 −

print("Categorical Index...\n",catIndex)

获取分类 −

print("\nDisplayingCategories from CategoricalIndex...\n",catIndex.categories)

示例

以下是代码 −

import pandas as pd

# CategoricalIndex is the Index based on an underlying Categorical
# Set the categories for the categorical using the "categories" parameter
# Treat the categorical as ordered using the "ordered" parameter
catIndex = pd.CategoricalIndex(
   ["p", "q", "r", "s","p", "q", "r", "s"], ordered=True, categories=["p", "q", "r", "s"]
)

# Display the Categorical Index
print("Categorical Index...\n",catIndex)

# Get the categories
print("\nDisplayingCategories from CategoricalIndex...\n",catIndex.categories)

# Get the min value
print("\nMinimum value from CategoricalIndex...\n",catIndex.min())

# Get the max value
print("\nMaximum value from CategoricalIndex...\n",catIndex.max())

输出

这将产生以下输出 −

Categorical Index...
CategoricalIndex(['p', 'q', 'r', 's', 'p', 'q', 'r', 's'], categories=['p', 'q', 'r', 's'], ordered=True, dtype='category')

DisplayingCategories from CategoricalIndex...
Index(['p', 'q', 'r', 's'], dtype='object')

Minimum value from CategoricalIndex...
p

Maximum value from CategoricalIndex...
S

更新于: 14-10-2021

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