import pandas as pd
 
#create DataFrame
df = pd.DataFrame({'points': [25, 12, 15, 14, 19],
                   'assists': [5, 7, 7, 9, 12],
                   'rebounds': [11, 8, 10, 6, 6]})
 
#view DataFrame
df
        points	assists	rebounds
0	25	5	11
1	12	7	8
2	15	7	10
3	14	9	6
4	19	12	6
 
#insert new column 'player' as first column
player_vals = ['A', 'B', 'C', 'D', 'E']
df.insert(loc=0, column='player', value=player_vals)
df
 
        player	points	assists	rebounds
0	A	25	5	11
1	B	12	7	8
2	C	15	7	10
3	D	14	9	6
4	E	19	12	6

示例 2：插入新列作為中間列

以下代碼顯示了如何插入一個新列作為現(xiàn)有 DataFrame 的第三列：

import pandas as pd
 
#create DataFrame
df = pd.DataFrame({'points': [25, 12, 15, 14, 19],
                   'assists': [5, 7, 7, 9, 12],
                   'rebounds': [11, 8, 10, 6, 6]})
 
#insert new column 'player' as third column
player_vals = ['A', 'B', 'C', 'D', 'E']
df.insert(loc=2, column='player', value=player_vals)
df
 
        points	assists	player	rebounds
0	25	5	A	11
1	12	7	B	8
2	15	7	C	10
3	14	9	D	6
4	19	12	E	6

示例 3：插入新列作為最后一列

以下代碼顯示了如何插入一個新列作為現(xiàn)有 DataFrame 的最后一列：

import pandas as pd
 
#create DataFrame
df = pd.DataFrame({'points': [25, 12, 15, 14, 19],
                   'assists': [5, 7, 7, 9, 12],
                   'rebounds': [11, 8, 10, 6, 6]})
 
#insert new column 'player' as last column
player_vals = ['A', 'B', 'C', 'D', 'E']
df.insert(loc=len(df.columns), column='player', value=player_vals)
df
 
        points	assists	player	rebounds
0	25	5	A	11
1	12	7	B	8
2	15	7	C	10
3	14	9	D	6
4	19	12	E	6

請注意，使用 len(df.columns) 允許您在任何數(shù)據(jù)幀中插入一個新列作為最后一列，無論它可能有多少列。

您可以在此處找到 insert() 函數(shù)的完整文檔。

補(bǔ)充：按條件選擇分組分別賦值

按條件先選擇數(shù)據(jù)，然后對這部分?jǐn)?shù)據(jù)賦值新列

實(shí)例：高低溫差大于10度，則認(rèn)為溫差大

# 先創(chuàng)建空列（這是第一種創(chuàng)建新列的方法）
df['wencha_type'] = ''

df.loc[df["bWendu"]-df["yWendu"]>10, "wencha_type"] = "溫差大"

df.loc[df["bWendu"]-df["yWendu"]<=10, "wencha_type"] = "溫差正常"