极客教程Python – 使用左外连接合并Pandas DataFrame
要合并Pandas DataFrame，请使用 merge ()函数。在merge()函数的“ how ”参数下设置左外连接即可同时在两个DataFrame上执行左外连接，即−
how = “left”Python
首先，让我们使用别名导入pandas库−
import pandas as pdPython
让我们创建两个要合并的DataFrame−
# 创建DataFrame1
dataFrame1 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Audi', 'Mustang', 'Bentley', 'Jaguar'],"Units": [100, 150, 110, 80, 110, 90]
}
)
# 创建DataFrame2
dataFrame2 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Tesla', 'Mustang', 'Mercedes', 'Jaguar'],"Reg_Price": [7000, 1500, 5000, 8000, 9000, 6000]
}
)
Python
使用公共列Car和”how”参数中的”left”实现左外连接合并数据帧−
mergedRes = pd.merge(dataFrame1, dataFrame2, on ='Car', how ="left")
Python
更多Pandas相关文章，请阅读：Pandas 教程
示例
以下是代码−
import pandas as pd
# 创建DataFrame1
dataFrame1 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Audi', 'Mustang', 'Bentley', 'Jaguar'],"Units": [100, 150, 110, 80, 110, 90]
}
)
print"DataFrame1 ...\n",dataFrame1
# 创建DataFrame2
dataFrame2 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Tesla', 'Mustang', 'Mercedes', 'Jaguar'],"Reg_Price": [7000, 1500, 5000, 8000, 9000, 6000]
}
)
print"\nDataFrame2 ...\n",dataFrame2
# merge DataFrames with common column Car and "left" in "how" parameter implements Left Outer Join
mergedRes = pd.merge(dataFrame1, dataFrame2, on ='Car', how ="left")
print"\nMerged dataframe with left outer join...\n", mergedResPython
输出
这将生成以下输出−
DataFrame1 ...
Car Units
0 BMW 100
1 Lexus 150
2 Audi 110
3 Mustang 80
4 Bentley 110
5 Jaguar 90
DataFrame2 ...
Car Reg_Price
0 BMW 7000
1 Lexus 1500
2 Tesla 5000
3 Mustang 8000
4 Mercedes 9000
5 Jaguar 6000
Merged dataframe with left outer join...
Car Units Reg_Price
0 BMW 100 7000.0
1 Lexus 150 1500.0
2 Audi 110 NaN
3 Mustang 80 8000.0
4 Bentley 110 NaN
5 Jaguar 90 6000.0
Python