CODEWITHSUNDEEP
pythonpython-3.x
Dinero
Dinero

Reputation: 1160

How to ignore strings that are not valid

import datetime

random_list = ["lol", "2020-10-05", "2020-09-11"]
date_list = []

for item in random_list:
    try:
        date = datetime.datetime.strptime(item, "%Y-%m-%d")
        date_list.append(date)
    except ValueError:
        print("Not a valid date foramt")


print(date_list)

In the above code, I am basically passing through some random_list and if i see a string that is of valid date format i want to add it another list called date_list.

I only want to add strings that are of valid date format meaning if i see a random string "foo" i want to ignore it and not append it to the date_list.

I guess what would be the best and most pythonic way to handle this?

Ideally if there were some boolean function that would tell me if the string i am looking at is a date then i would be able to just append strings to date_list when they return True upon validation.

I would love some thoughts on the correct way i can handle this.

Upvotes: 0

Views: 139

Answers (2)

F1Rumors
F1Rumors

Reputation: 948

Well, as you are using the specific format YYYY-MM-DD you can trivially do it via regular expressions. Something like this:

import re
import datetime
rDate = re.compile(r'^\d\d\d\d-\d\d-\d\d$')

isDate = lambda d: rDate.match(d)
toDate = lambda d: datetime.datetime.strptime(d, "%Y-%m-%d")

random_list = ["lol", "2020-10-05", "2020-09-11"]
date_list = list(map(toDate, filter(isDate, random_list)))

print(date_list)

I get this result:

$ /bin/python ./dates.py
[datetime.datetime(2020, 10, 5, 0, 0), datetime.datetime(2020, 9, 11, 0, 0)]

Upvotes: 1

Ironkey
Ironkey

Reputation: 2607

thats a pretty good way to do it, you could implement it using a list comprehension or using the filter function

random_list = ["lol", "2020-10-05", "2020-09-11"]

def validate(date_text):
    try: datetime.datetime.strptime(date_text, '%Y-%m-%d'); return True
    except ValueError: return False

random_list = list(filter(validate, random_list))

print(random_list)

#or 

[i for i in random_list if validate(i)]

both will give you:

["2020-10-05", "2020-09-11"]

if you want to convert its easiest to use the list comprehension with filter

[datetime.datetime.strptime(i, '%Y-%m-%d') for i in list(filter(validate, random_list))]

[datetime.datetime(2020, 10, 5, 0, 0), datetime.datetime(2020, 9, 11, 0, 0)]

Upvotes: 1

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