使用 Python 在 Pandas 数据框中创建星期几列 [英] Create a day-of-week column in a Pandas dataframe using Python

问题描述

使用 Python 在 Pandas 数据框中创建星期几列

Create a day-of-week column in a Pandas dataframe using Python

我想将一个 csv 文件读入一个 Pandas 数据帧，将一列日期从字符串格式解析为一个日期对象，然后生成一个新的列来表示星期几.

I’d like to read a csv file into a pandas dataframe, parse a column of dates from string format to a date object, and then generate a new column that indicates the day of the week.

这就是我正在尝试的:

我想做的是:

import pandas as pd

import csv

df = pd.read_csv('data.csv', parse_dates=['date']))

df['day-of-week'] = df['date'].weekday()


AttributeError: 'Series' object has no attribute 'weekday'

<小时>

感谢您的帮助.詹姆斯

---

Thank you for your help. James

推荐答案

Pandas 0.23+

使用 pandas.Series.dt.day_name()，因为 pandas.Timestamp.weekday_name 已被弃用:

import pandas as pd


df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])

df['day_of_week'] = df['my_dates'].dt.day_name()

输出:

    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

熊猫 0.18.1+

正如用户 jezrael 在下面指出的，dt.weekday_name 是在 0.18.1 版本中添加的Pandas 文档

Pandas 0.18.1+

As user jezrael points out below, dt.weekday_name was added in version 0.18.1 Pandas Docs

import pandas as pd

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])
df['day_of_week'] = df['my_dates'].dt.weekday_name

输出:

    my_dates  myvals day_of_week
0 2015-01-01       1    Thursday
1 2015-01-02       2      Friday
2 2015-01-03       3    Saturday

原答案:

使用这个:

http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.dt.dayofweek.html

看到这个:

获取 DataFrame 的日期时间列的工作日/星期几

如果你想要一个字符串而不是一个整数，请执行以下操作:

If you want a string instead of an integer do something like this:

import pandas as pd

df = pd.DataFrame({'my_dates':['2015-01-01','2015-01-02','2015-01-03'],'myvals':[1,2,3]})
df['my_dates'] = pd.to_datetime(df['my_dates'])
df['day_of_week'] = df['my_dates'].dt.dayofweek

days = {0:'Mon',1:'Tues',2:'Weds',3:'Thurs',4:'Fri',5:'Sat',6:'Sun'}

df['day_of_week'] = df['day_of_week'].apply(lambda x: days[x])

输出:

    my_dates  myvals day_of_week
0 2015-01-01       1       Thurs
1 2015-01-02       2         Fri
2 2015-01-01       3       Thurs

这篇关于使用 Python 在 Pandas 数据框中创建星期几列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！