I have Pandas dateframe which has two column; ID and dates. Additionally, I have a dictionary with start and end date and I want to extract data from Pandas dataframe which is between dictionary values.

Below is my data.

1. Dataframe (df)

2. Dictioary date_dictionary = {'start_date':'20020101', 'end_date':'20101231'}

If I use,

extracted = df.query('20020101<=Dates<=20101231')

then it works. But I wonder why the following code gave me an error; UndefinedVariableError: name 'start_date' is not defined.

start_date=int(date_dictionary['start_date'])
end_date=int(date_dictionary['end_date'])
extracted = df.query('start_date<=Dates<=end_date')

I imported 'date_dictionary' using from date_dictionary import *.

Please someone why it doesn't work. And is there any method using dictionary's value inside the query statement?

CodePudding user response：

You can refer to variables in the expression by prefixing them with an ‘@’:

extracted = df.query("@start_date<=Dates<=@end_date")

   ID     Dates
1   2  20091212
2   3  20020924

Have a look at the documentation of query