Pandas/Python：基于行值和其他数据帧设置新列的值

当第二个数据帧的省名称与第一个数据帧的省名称匹配时，是否可以在列中添加值？我在寻找答案，却找不到任何对我的案子有用的东西

这是第一个数据帧

    date        province            confirmed   released    deceased
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0
...

    code    province            latitude    longitude
0   12000   Daegu               35.872150   128.601783   
1   60000   Gyeongsangbuk-do    36.576032   128.505599  
2   20000   Gyeonggi-do         37.275119   127.009466
3   10000   Seoul               37.566953   126.977977  
4   41000   Chungcheongnam-do   36.658976   126.673318
...

    date        province            confirmed   released    deceased    latitude     longitude
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318

这是第二个数据帧

    date        province            confirmed   released    deceased
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0
...

    code    province            latitude    longitude
0   12000   Daegu               35.872150   128.601783   
1   60000   Gyeongsangbuk-do    36.576032   128.505599  
2   20000   Gyeonggi-do         37.275119   127.009466
3   10000   Seoul               37.566953   126.977977  
4   41000   Chungcheongnam-do   36.658976   126.673318
...

    date        province            confirmed   released    deceased    latitude     longitude
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318

我想把第一个数据帧变成这样

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318
...

谢谢

该方法就是您希望在此处使用的方法

使用示例数据帧：

import pandas as pd

df1 = pd.DataFrame(dict(
    date = [
        '2020-03-30','2020-03-30','2020-03-30',
        '2020-03-30','2020-03-30',],
    province = [
        'Daegu', 'Gyeongsangbuk-do', 'Gyeonggi-do', 
        'Seoul', 'Chungcheongnam-do'],
    confirmed = [6624, 1298, 463, 426, 127],
    released = [3837, 772, 160, 92, 83],
    deceased = [111, 38, 5, 0, 0],
))

df2 = pd.DataFrame(dict(
    code = [12000, 60000, 20000, 10000, 41000],
    province = [
        'Daegu', 'Gyeongsangbuk-do', 'Gyeonggi-do', 
        'Seoul', 'Chungcheongnam-do'],
    latitude = [
        35.872150, 36.576032, 37.275119, 
        37.566953, 36.658976],
    longitude = [
        128.601783, 128.505599, 127.009466, 
        126.977977, 126.673318],
))

df3 =  df1.merge(
    df2[['province', 'latitude','longitude']],
    on = 'province',
)

pd.set_option('display.max_columns', 7)

print(df3)

         date           province  confirmed  released  deceased   latitude  \
0  2020-03-30              Daegu       6624      3837       111  35.872150   
1  2020-03-30   Gyeongsangbuk-do       1298       772        38  36.576032   
2  2020-03-30        Gyeonggi-do        463       160         5  37.275119   
3  2020-03-30              Seoul        426        92         0  37.566953   
4  2020-03-30  Chungcheongnam-do        127        83         0  36.658976   

    longitude  
0  128.601783  
1  128.505599  
2  127.009466  
3  126.977977  
4  126.673318

输出：

import pandas as pd

df1 = pd.DataFrame(dict(
    date = [
        '2020-03-30','2020-03-30','2020-03-30',
        '2020-03-30','2020-03-30',],
    province = [
        'Daegu', 'Gyeongsangbuk-do', 'Gyeonggi-do', 
        'Seoul', 'Chungcheongnam-do'],
    confirmed = [6624, 1298, 463, 426, 127],
    released = [3837, 772, 160, 92, 83],
    deceased = [111, 38, 5, 0, 0],
))

df2 = pd.DataFrame(dict(
    code = [12000, 60000, 20000, 10000, 41000],
    province = [
        'Daegu', 'Gyeongsangbuk-do', 'Gyeonggi-do', 
        'Seoul', 'Chungcheongnam-do'],
    latitude = [
        35.872150, 36.576032, 37.275119, 
        37.566953, 36.658976],
    longitude = [
        128.601783, 128.505599, 127.009466, 
        126.977977, 126.673318],
))

df3 =  df1.merge(
    df2[['province', 'latitude','longitude']],
    on = 'province',
)

pd.set_option('display.max_columns', 7)

print(df3)

         date           province  confirmed  released  deceased   latitude  \
0  2020-03-30              Daegu       6624      3837       111  35.872150   
1  2020-03-30   Gyeongsangbuk-do       1298       772        38  36.576032   
2  2020-03-30        Gyeonggi-do        463       160         5  37.275119   
3  2020-03-30              Seoul        426        92         0  37.566953   
4  2020-03-30  Chungcheongnam-do        127        83         0  36.658976   

    longitude  
0  128.601783  
1  128.505599  
2  127.009466  
3  126.977977  
4  126.673318

---

您真正想要做的是基于

省

列合并两个数据帧

创建一个您想要的新数据帧

首先在第一个数据帧上运行一个循环，并添加其中的所有值。（保留不存在的列的值）

然后在第二个数据帧上运行一个循环，并通过比较

province

的值与新数据帧中已经添加的值来添加its值

这里有一个例子

新数据帧

    date        province            confirmed   released    deceased
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0
...

    code    province            latitude    longitude
0   12000   Daegu               35.872150   128.601783   
1   60000   Gyeongsangbuk-do    36.576032   128.505599  
2   20000   Gyeonggi-do         37.275119   127.009466
3   10000   Seoul               37.566953   126.977977  
4   41000   Chungcheongnam-do   36.658976   126.673318
...

date        province            confirmed   released    deceased   latitude     longitude

    date        province            confirmed   released    deceased    latitude     longitude
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318

在添加第一个数据帧之后

    date        province            confirmed   released    deceased
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0
...

    code    province            latitude    longitude
0   12000   Daegu               35.872150   128.601783   
1   60000   Gyeongsangbuk-do    36.576032   128.505599  
2   20000   Gyeonggi-do         37.275119   127.009466
3   10000   Seoul               37.566953   126.977977  
4   41000   Chungcheongnam-do   36.658976   126.673318
...

    date        province            confirmed   released    deceased    latitude     longitude
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318

在添加第二个数据帧之后

    date        province            confirmed   released    deceased
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0
...

    code    province            latitude    longitude
0   12000   Daegu               35.872150   128.601783   
1   60000   Gyeongsangbuk-do    36.576032   128.505599  
2   20000   Gyeonggi-do         37.275119   127.009466
3   10000   Seoul               37.566953   126.977977  
4   41000   Chungcheongnam-do   36.658976   126.673318
...

    date        province            confirmed   released    deceased    latitude     longitude
0   2020-03-30  Daegu               6624        3837        111
1   2020-03-30  Gyeongsangbuk-do    1298        772         38
2   2020-03-30  Gyeonggi-do         463         160         5
3   2020-03-30  Seoul               426         92          0
4   2020-03-30  Chungcheongnam-do   127         83          0

    date        province            confirmed   released    deceased   latitude     longitude
0   2020-03-30  Daegu               6624        3837        111        35.872150    128.601783
1   2020-03-30  Gyeongsangbuk-do    1298        772         38         36.576032    128.505599
2   2020-03-30  Gyeonggi-do         463         160         5          37.275119    127.009466
3   2020-03-30  Seoul               426         92          0          37.566953    126.977977
4   2020-03-30  Chungcheongnam-do   127         83          0          36.658976    126.673318

---

我感谢你的帮助！