Question

我正在尝试在数据框的左侧添加一列。默认情况下，它似乎添加到右侧。有没有办法在左侧添加列？

这是我的代码：

import pandas as pd
import numpy as np
df = pd.read_csv("/home/Sample Text Files/sample5.csv", delimiter = "\t")
df=pd.DataFrame(df)
df['Creation_DT']=pd.to_datetime('today')
print(df)

以下是输出：

 ID,Name,Age                Creation_DT
0  1233,Maliva,15 2019-07-17 11:11:37.145194

我希望输出如下：

Creation_DT, ID, Name, Age
[value], [Value], [Value], [Value]

Answer 1

您可以添加一行代码来重新排列列，如下所示：

    import re
    imports pandas as pd

    # my df has these columns, wehre body contains the email chains
    df = pd.DataFrame(columns=['thread_id', 'body', 'from', 'message_sent_date'])

    example_id = 1

    email1 = df.iloc[example_id]['body']
    email_stripped = strip_html(email1)
    email_stripped = email_stripped.replace('>', '')
    from_name1 = df.iloc[example_id]['from_name']
    from_email_address = df.iloc[example_id]['from']

    match_on_date_intro2 = "On [^\n\r]* wrote:"
    match_on_email_intro = 'From: ' + from_name1 + ' <' + from_email_address
    match_original_msg = '--Original Message--'
    regex_to_match = ('(' 
                      #+ match_on_date_intro 
                      #+ '|' 
                      + match_on_email_intro 
                      + '|' 
                      + match_on_date_intro2 
                      + '|' 
                      + match_original_msg
                      + ')'
                     )
    l = re.compile(regex_to_match).split(email_stripped)
    print("<<<<<<============= MESSAGE STARTING =========>>>>>>")

    for x in l:
        print("============= NEXT MESSAGE =========")
        print(x)

另一个选择是在转换期间插入列：

df = df[['Creation_DT', 'ID', 'Name', 'Age']]

Answer 2

尝试df.insert将列放置在特定数据上

df.insert(loc=0, column='Creation_DT', value=pd.to_datetime('today'))

如何在数据框的左侧添加列，e

2 个答案: