Python Pandas - 如何在特定级别对 MultiIndex 进行排序
要创建MultiIndex，请使用from_arrays()方法。但是，要在特定级别对MultiIndex进行排序，请使用Pandas中的方法。将级别设置为参数。multiIndex.sortlevel()
首先，导入所需的库-
import pandas as pd
MultiIndex是Pandas对象的多级或分层索引对象。创建数组：
arrays = [[2, 4, 3, 1], ['Peter', 'Chris', 'Andy', 'Jacob']]
“names”参数设置每个索引级别的名称。将from_arrays()被用来创建一个多指标-
multiIndex = pd.MultiIndex.from_arrays(arrays, names=('ranks', 'student'))排序多索引。要排序的特定级别设置为参数，即此处的级别1-
print("\nSort MultiIndex at the requested level...\n",multiIndex.sortlevel(1))示例
以下是代码-
import pandas as pd
#MultiIndexisamulti-level,orhierarchical,indexobjectforpandasobjects
#Createarrays
arrays = [[2, 4, 3, 1], ['Peter', 'Chris', 'Andy', 'Jacob']]
# The "names" parameter sets the names for each of the index levels
#Thefrom_arrays()isusedtocreateaMultiIndex
multiIndex = pd.MultiIndex.from_arrays(arrays, names=('ranks', 'student'))
#displaytheMultiIndex
print("The Multi-index...\n",multiIndex)
#getthelevelsinMultiIndex
print("\nThe levels in Multi-index...\n",multiIndex.levels)
#SortMultiIndex
#Thespecificleveltosortissetasaparameteri.e.level1here
print("\nSort MultiIndex at the requested level...\n",multiIndex.sortlevel(1))输出结果这将产生以下输出-
The Multi-index...
MultiIndex([(2, 'Peter'),
(4, 'Chris'),
(3, 'Andy'),
(1, 'Jacob')],
names=['ranks', 'student'])
The levels in Multi-index...
[[1, 2, 3, 4], ['Andy', 'Chris', 'Jacob', 'Peter']]
Sort MultiIndex at the requested level...
(MultiIndex([(3, 'Andy'),
(4, 'Chris'),
(1, 'Jacob'),
(2, 'Peter')],
names=['ranks', 'student']), array([2, 1, 3, 0], dtype=int64))