pandas 过滤和比较日期 [英] pandas filtering and comparing dates

问题描述

我有一个sql文件，其中包含我要读入熊猫的数据.

I have a sql file which consists of the data below which I read into pandas.

df = pandas.read_sql('Database count details', con=engine,
                     index_col='id', parse_dates='newest_available_date')

输出

id       code   newest_date_available
9793708  3514   2015-12-24
9792282  2399   2015-12-25
9797602  7452   2015-12-25
9804367  9736   2016-01-20
9804438  9870   2016-01-20

代码的下一行是获取上周的日期

The next line of code is to get last week's date

date_before = datetime.date.today() - datetime.timedelta(days=7) # Which is 2016-01-20

我想做的是，将date_before与df进行比较，并打印出所有小于date_before

What I am trying to do is, to compare date_before with df and print out all rows that is less than date_before

if (df['newest_available_date'] < date_before): print(#all rows)

if (df['newest_available_date'] < date_before): print(#all rows)

显然，这会给我返回错误The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Obviously this returns me an error The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

我应该怎么做?

推荐答案

我会做一个面具:

a = df[df['newest_date_available'] < date_before]

如果为date_before = datetime.date(2016, 1, 19)，则返回:

        id  code newest_date_available
0  9793708  3514            2015-12-24
1  9792282  2399            2015-12-25
2  9797602  7452            2015-12-25

这篇关于 pandas 过滤和比较日期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！