Python Pandas - 使用层名称删除多层次的 MultiIndex

要使用层名称删除多层次的 MultiIndex，请使用 MultiIndex.droplevel() 方法，并将其所要删除的多层（层名称）设置为参数。

首先，导入所需的库。

import pandas as pd

MultiIndex 是 pandas 对象的多层或层次索引对象。创建数组。

arrays = [[2, 4, 3, 1], ['Peter', 'Chris', 'Andy', 'Jacob'], [50, 30, 40, 70]]

“names”参数为各个索引层设置名称。from_arrays() 用于创建 MultiIndex。

multiIndex = pd.MultiIndex.from_arrays(arrays, names=('rank', 'student', 'points'))

从 MultiIndex 中删除特定层。被删除的层在参数中设置为层名称，即层名称“student”和“rank”被删除。

print("\nMulti-index after dropping two levels...\n",multiIndex.droplevel(['rank', 'student']))

示例

以下为代码。

import pandas as pd

# MultiIndex is a multi-level, or hierarchical, index object for pandas objects
# Create arrays
arrays = [[2, 4, 3, 1], ['Peter', 'Chris', 'Andy', 'Jacob'], [50, 30, 40, 70]]

# The "names" parameter sets the names for each of the index levels
# The from_arrays() is used to create a MultiIndex
multiIndex = pd.MultiIndex.from_arrays(arrays, names=('rank', 'student', 'points'))

# display the MultiIndex
print("The Multi-index...\n",multiIndex)

# get the levels in MultiIndex
print("\nThe levels in Multi-index...\n",multiIndex.levels)

# Drop a specific level from MultiIndex
# The levels to be dropped is set as the level names in parameter i.e.
# level name 'student' and 'rank' gets dropped
print("\nMulti-index after dropping two levels...\n",multiIndex.droplevel(['rank', 'student']))

输出

将生成以下输出。

The Multi-index...
MultiIndex([(2, 'Peter', 50),
            (4, 'Chris', 30),
            (3,  'Andy', 40),
            (1, 'Jacob', 70)],
            names=['rank', 'student', 'points'])

The levels in Multi-index...
   [[1, 2, 3, 4], ['Andy', 'Chris', 'Jacob', 'Peter'], [30, 40, 50, 70]]

Multi-index after dropping two levels...
   Int64Index([50, 30, 40, 70], dtype='int64', name='points')

AmitDiwan

更新日期：2021-10-19

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