Pandas中pivot_table()与拼接的快速实现

import pandas as pd

data = {
    'City': ['New York', 'New York', 'Chicago', 'Chicago', 'Los Angeles', 'Los Angeles'],
    'Product': ['A', 'B', 'A', 'B', 'A', 'B'],
    'Sales': [100, 200, 150, 250, 120, 180]
}

df = pd.DataFrame(data)

pivot_df = df.pivot_table(index='City', columns='Product', values='Sales', aggfunc='sum')
print(pivot_df)

Product    A    B
City                
Chicago   150  250
Los Angeles  120  180
New York  100  200

data1 = {
    'Date': ['2021-01-01', '2021-01-02'],
    'Sales': [100, 200]
}

data2 = {
    'Date': ['2021-01-03', '2021-01-04'],
    'Sales': [150, 250]
}

df1 = pd.DataFrame(data1)
df2 = pd.DataFrame(data2)

concat_df = pd.concat([df1, df2], ignore_index=True)
print(concat_df)

         Date  Sales
0  2021-01-01    100
1  2021-01-02    200
2  2021-01-03    150
3  2021-01-04    250

pivot_df.fillna(0, inplace=True)  # 用 0 填充空值

concat_df.reset_index(drop=True, inplace=True)