pandas 系列中的日期数据排序 [英] Sorting date data in pandas Series

问题描述

数据如下:

0        Thursday
1        Thursday
2        Thursday
3        Thursday
etc, etc

我的代码:

import pandas as pd
data_file = pd.read_csv('./data/Chicago-2016-Summary.csv')
days = data_file['day_of_week']

order = ["Monday","Tuesday","Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]

sorted(days, key=lambda x: order.index(x[0]))
print(days)

这将导致错误:

ValueError:"T"不在列表中

ValueError: 'T' is not in list

我试图进行排序并得到此错误，但我不知道这意味着什么.

I tried to sort and get this error but I have no idea what this means.

我只想对周一至周日的数据进行排序，以便可以进行一些可视化处理.有什么建议吗?

I just want to sort the data Monday-Sunday so I can do some visualizations. Any suggestions?

推荐答案

您可以为此使用熊猫的Categorical数据类型:

You can use pandas' Categorical data type for this:

order = ["Monday","Tuesday","Wednesday", "Thursday", "Friday", "Saturday", "Sunday"] 
data_file['day_of_week'] = pd.Categorical(data_file['day_of_week'], categories=order, ordered=True)
data_file.sort_values(by='day_of_week', inplace=True)

在您的示例中，请注意，当您指定

In your example, be aware that when you specify

days = data_file['day_of_week']

您正在创建data_file框架中该列(系列)的视图.您可能要使用days = data_file['day_of_week'].copy().或者，只需像上面那样在DataFrame中工作.

you are creating a view to that column (Series) within your data_file frame. You may want to use days = data_file['day_of_week'].copy(). Or, just work within the DataFrame as is done above.

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