How to subtract dates from eachother (python)-CodePudding

I have the following code:

    for dictionary in ministers:
        if(math.floor((datetime.date.today() - dictionary[3]).days/365.25) <50):
            print(dictionary[1], dictionary[2], math.floor((datetime.datetime.today() - dictionary[3]).days/365.25))

I am supposed to take today's date and subtract that with a date given in a list of dictionaries. Here is that list of dictionaries:

 ministers = [{1: "Alexander", 2: "De Croo", 3: "3-11-1975", 4: "Vilvoorde", 5: "Open Vld"},
             {1: "Sophie", 2: "Wilmès", 3: "15-01-1975", 4: "Elsene", 5: "MR"},
             {1: "Frank", 2: "Vandenbroucke", 3: "21-10-1955", 4: "Leuven", 5: "sp.a"},
             {1: "Petra", 2: "De Sutter", 3: "10-6-1963", 4: "Oudenaarde", 5: "groen"},
             {1: "Sammy", 2: "Mahdi", 3: "21-9-1988", 4: "Elsene", 5: "CD&V"},
             {1: "Zakia", 2: "Khattabi", 3: "15-1-1976", 4: "Sint-Joost-ten-Node", 5: "Ecolo"},
             {1: "Ludivine", 2: "Dedonder", 3: "17-3-1977", 4: "Doornik", 5: "PS"},
             {1: "Karine", 2: "Lalieux", 3: "4-5-1964", 4: "Anderlecht", 5: "PS"},]

If the resulted number is smaller than 50 than I am supposed to indicate that. But it is impossible to subtract 2 dates from eachother like this, I'm aware of that but I can't find any fix or way around this. I'm still very new to python and programming in general.

This is the resulting error: TypeError: unsupported operand type(s) for -: 'datetime.date' and 'str'

I have tried converting the dates into an int or float, but this doesn't work either.

CodePudding user response：

As the error message is saying, your subtraction does not work because you are trying to subtract a string from a date, and python does not know how to do it.

The solution is to subtract date from a date, like in this example:

date_1 = datetime.date(2019, 1, 1)
date_2 = datetime.date(2018, 11, 10)

print(date_2 - date_1)

# prints -52 days, 0:00:00

Now to get there, you will need to convert the strings such as "15-1-1975" to dates. For this use the following function:

date = datetime.datetime.strptime("15-1-1976", "%d-%m-%Y")

CodePudding user response：

This is an approximate solution to your problem:

from datetime import datetime, timedelta

today = datetime.now()

ministers = [
     {1: "Alexander", 2: "De Croo", 3: "3-11-1975", 4: "Vilvoorde", 5: "Open Vld"},
     {1: "Sophie", 2: "Wilmès", 3: "15-01-1975", 4: "Elsene", 5: "MR"},
     {1: "Frank", 2: "Vandenbroucke", 3: "21-10-1955", 4: "Leuven", 5: "sp.a"},
     {1: "Petra", 2: "De Sutter", 3: "10-6-1963", 4: "Oudenaarde", 5: "groen"},
     {1: "Sammy", 2: "Mahdi", 3: "21-9-1988", 4: "Elsene", 5: "CD&V"},
     {1: "Zakia", 2: "Khattabi", 3: "15-1-1976", 4: "Sint-Joost-ten-Node", 5: "Ecolo"},
     {1: "Ludivine", 2: "Dedonder", 3: "17-3-1977", 4: "Doornik", 5: "PS"},
     {1: "Karine", 2: "Lalieux", 3: "4-5-1964", 4: "Anderlecht", 5: "PS"}
]

for minister in ministers:
    dob = datetime.strptime(minister[3], '%d-%m-%Y')
    if today - dob < timedelta(days=18250):
        print(f"Minister {minister[1]} is younger than 50")