python - 按列值连接两个数据框

Question

如何使用日期列连接这两个数据框，而无需重复许多行:

data = {'date':['01/01/2018', '02/02/2019', '01/04/2019', '16/02/2019','20/03/2019'], 'Age':[20, 21, 19, 18,34]} 

# Create DataFrame 
df1 = pd.DataFrame(data) 
df1

DF2

data2 = {'date':['01/01/2018', '04/07/2019', '01/04/2019', '18/02/2018'], 'miles':[50, 81, 99, 109]} 

# Create DataFrame 
df2 = pd.DataFrame(data2) 
df2

最终结果应如下所示:

finaldata = {'date':['01/01/2018', '02/02/2019', '01/04/2019', '16/02/2019','20/03/2019'], 'Age':[20, 21, 19, 18,34], 'miles':[50, 'NAN', 99, 'NAN', 'NAN']} 

# Create DataFrame 
final_df = pd.DataFrame(finaldata) 
final_df

我已在我的数据集上尝试过此代码，但它创建了很多重复的行

df1.merge(df2)

Answer 1

使用“如何”参数:

df1.merge(df2, how='left')

https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.merge.html