Python Pandas - 使用 MultiIndex 中的级别名称重新排列级别

要使用 MultiIndex 中的级别名称重新排列级别，请在 Pandas 中使用 MultiIndex.reorder_levels() 方法。将要重新排列的级别（级别名称）作为参数传递。

首先，导入所需的库 −

import pandas as pd

MultiIndex 是 pandas 对象的多级或层次索引对象。创建数组 -

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

"names" 参数设置每个索引级别的名称。from_arrays() 用于创建 MultiIndex -

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

重新排序 MultiIndex 的级别。 "order" 参数用于设置级别名称，以便重新排序级别 −

print("\nReorder levels in MultiIndex using level name...\n",multiIndex.reorder_levels(order=['student','rank','points']))

示例

以下是代码 -

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 MultiIndex...\n",multiIndex)

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

# swap levels of MultiIndex using swaplevel()
# The 1st parameter is the first level of index to be swapped
# The 2nd parameter is the second level of index to be swapped
print("\nSwap levels in MultiIndex...\n",multiIndex.swaplevel(0,2))

# Reorder levels of MultiIndex
# The "order" parameter is used to set the level name in a form to reorder levels
print("\nReorder levels in MultiIndex using level name...\n",multiIndex.reorder_levels(order=['student','rank','points']))

输出

这将产生以下输出 -

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

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

Swap levels in MultiIndex...
MultiIndex([('Peter', 2, 50),
            ('Chris', 4, 30),
            ( 'Andy', 3, 40),
            ('Jacob', 1, 70)],
            names=['student', 'rank', 'points'])

Reorder levels in MultiIndex using level name...
MultiIndex([('Peter', 2, 50),
            ('Chris', 4, 30),
            ( 'Andy', 3, 40),
            ('Jacob', 1, 70)],
            names=['student', 'rank', 'points'])

更新时间： 19-Oct-2021

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