使用Python在Pandas数据框中创建一个星期列 [英] Create a day-of-week column in a Pandas dataframe using Python

问题描述

使用Python在Pandas数据框中创建一个星期列列表

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

我想将一个csv文件读入熊猫数据框，解析一列日期从字符串格式到日期对象，然后生成一个新的列，指示一周中的某一天。

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.

这是我正在尝试的：

我想做的是这样的：

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'

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感谢您的帮助。
James

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Thank you for your help. James

推荐答案

编辑：

下面指出， dt.weekday_name 已添加到版本0.18.1
熊猫文档

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

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原始答案：

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Original Answer:

使用这个：

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

请参阅：

获取DataFrame的Datetime列的工作日/星期几

如果你想一个字符串而不是一个整数做这样的事情：

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

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