Python Pandas CategoricalIndex - 类似于 dict 一样使用输入对应关系映射值


要使用类似于 dict 的输入对应关系映射值,请在 Pandas 中使用 CategoricalIndex.map() 方法。首先导入所需的库 −

import pandas as pd

使用 "categories" 参数设置分类的类别。使用 "ordered" 参数将分类视为有序的 −

catIndex = pd.CategoricalIndex(["P", "Q", "R", "S","P", "Q", "R", "S"], ordered=True, categories=["P", "Q", "R", "S"])

显示 CategoricalIndex −

print("CategoricalIndex...\n",catIndex)

映射类别 −

print("\nCategoricalIndex after mapping...\n",catIndex.map({'P': 5, 'Q': 10, 'R': 15, 'S': 20}))

示例

以下是代码 −

import pandas as pd

# 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 CategoricalIndex
print("CategoricalIndex...\n",catIndex)

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

# Map categories
print("\nCategoricalIndex after mapping...\n",catIndex.map({'P': 5, 'Q': 10, 'R': 15, 'S': 20}))

输出

这将产生以下输出 −

CategoricalIndex...
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')

CategoricalIndex after mapping...
CategoricalIndex([5, 10, 15, 20, 5, 10, 15, 20], categories=[5, 10, 15, 20], ordered=True, dtype='category')

更新于: 18-Oct-2021

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