python - 如何在 pandas 数据框中连接多个文本字段

Question

如何将 pandas 数据帧的某些文本列的唯一值连接到单个列中。例如:

data = [[1,"US","California","Los Angeles"],
        [1,"US","California","San Francisco"],
        [1,"US","California","San Diego"],
        [1,"US","Texas","Austin"],
        [2,"IND","Maharashtra","Mumbai"],
        [2,"IND","Maharashtra","Pune"],
        [2,"IND","Maharashtra","Nagpur"]]

df = pd.DataFrame(data, columns = ['Country_Id', 'Country','State','Place'])

从上面的数据框中，如何生成一个字段为 Country_Id 的输出第二个是包含唯一值 Country 的文本字段, State , Place .

喜欢:

• 1、美国加利福尼亚州德克萨斯州洛杉矶旧金山圣地亚哥奥斯汀
• 2，IND 马哈拉施特拉邦 孟买 浦那 那格浦尔

请忽略组合文本字段的含义

Answer 1

在unique和genexp上使用groupby和apply以及双重join

df.groupby('Country_Id').apply(lambda x: ' '.join(' '.join(x[col].unique()) for col in x))
                        .to_frame('Country-State-Place')


Out[434]:
                                                       Country-State-Place
Country_Id
1           US California Texas Los Angeles San Francisco San Diego Austin
2           IND Maharashtra Mumbai Pune Nagpur