Pandas DataFrame 刪除索引
Suraj Joshi
2023年1月30日
2021年1月22日
本教程將介紹如何刪除 Pandas DataFrame 的索引。
我們將使用下面顯示的 DataFrame 來展示如何刪除索引。
import pandas as pd
my_df = pd.DataFrame({
'Person': ['Alice', 'Steven', 'Neesham', 'Chris', 'Alice'],
'City': ['Berlin', 'Montreal', 'Toronto', 'Rome', 'Munich'],
'Mother Tongue': ['German', 'French', 'English', 'Italian', 'German'],
'Age': [37, 20, 38, 23, 35],
},index=["A","B","C","D","E"])
print(my_df)
輸出：
Person City Mother Tongue Age
A Alice Berlin German 37
B Steven Montreal French 20
C Neesham Toronto English 38
D Chris Rome Italian 23
E Alice Munich German 35
使用 reset_index() 方法刪除 Pandas DataFrame 的索引
pandas.DataFrame.reset_index() 會將 DataFrame 的索引重置為預設索引。
import pandas as pd
my_df = pd.DataFrame({
'Person': ['Alice', 'Steven', 'Neesham', 'Chris', 'Alice'],
'City': ['Berlin', 'Montreal', 'Toronto', 'Rome', 'Munich'],
'Mother Tongue': ['German', 'French', 'English', 'Italian', 'German'],
'Age': [37, 20, 38, 23, 35],
},index=["A","B","C","D","E"])
df_reset=my_df.reset_index()
print("Before reseting Index:")
print(my_df,"\n")
print("After reseting Index:")
print(df_reset)
輸出：
Before reseting Index:
Person City Mother Tongue Age
A Alice Berlin German 37
B Steven Montreal French 20
C Neesham Toronto English 38
D Chris Rome Italian 23
E Alice Munich German 35
After reseting Index:
index Person City Mother Tongue Age
0 A Alice Berlin German 37
1 B Steven Montreal French 20
2 C Neesham Toronto English 38
3 D Chris Rome Italian 23
4 E Alice Munich German 35
它將重置 DataFrame 的索引，但現在的索引將顯示為 index 列。如果我們想刪除 index 列，我們可以在 reset_index() 方法中設定 drop=True。
import pandas as pd
my_df = pd.DataFrame({
'Person': ['Alice', 'Steven', 'Neesham', 'Chris', 'Alice'],
'City': ['Berlin', 'Montreal', 'Toronto', 'Rome', 'Munich'],
'Mother Tongue': ['German', 'French', 'English', 'Italian', 'German'],
'Age': [37, 20, 38, 23, 35],
},index=["A","B","C","D","E"])
df_reset=my_df.reset_index(drop=True)
print("Before reseting Index:")
print(my_df,"\n")
print("After reseting Index:")
print(df_reset)
輸出：
Before reseting Index:
Person City Mother Tongue Age
A Alice Berlin German 37
B Steven Montreal French 20
C Neesham Toronto English 38
D Chris Rome Italian 23
E Alice Munich German 35
After reseting Index:
Person City Mother Tongue Age
0 Alice Berlin German 37
1 Steven Montreal French 20
2 Neesham Toronto English 38
3 Chris Rome Italian 23
4 Alice Munich German 35
使用 set_index() 方法刪除 Pandas DataFrame 的索引
pandas.DataFrame.set_index() 將把作為引數傳遞的列設定為 DataFrame 的索引，覆蓋初始索引。
import pandas as pd
my_df = pd.DataFrame({
'Person': ['Alice', 'Steven', 'Neesham', 'Chris', 'Alice'],
'City': ['Berlin', 'Montreal', 'Toronto', 'Rome', 'Munich'],
'Mother Tongue': ['German', 'French', 'English', 'Italian', 'German'],
'Age': [37, 20, 38, 23, 35],
},index=["A","B","C","D","E"])
df_reset=my_df.set_index('Person')
print("Initial DataFrame:")
print(my_df,"\n")
print("After setting Person column as Index:")
print(df_reset)
輸出：
Initial DataFrame:
Person City Mother Tongue Age
A Alice Berlin German 37
B Steven Montreal French 20
C Neesham Toronto English 38
D Chris Rome Italian 23
E Alice Munich German 35
After setting Person column as Index:
City Mother Tongue Age
Person
Alice Berlin German 37
Steven Montreal French 20
Neesham Toronto English 38
Chris Rome Italian 23
Alice Munich German 35
它將 Person 列設定為 my_df DataFrame 的索引，覆蓋了 DataFrame 的初始索引。
Author: Suraj Joshi
Suraj Joshi is a backend software engineer at Matrice.ai.
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