I developed a function that, from a given sequence of digits, extracts the date and reformat it.
This is the code:
from datetime import datetime as dt def format_dates(field): n = len(field) match = False i = 0 while match is False: try: # Take the last four digits year = int(field[-4 - i:n - i]) except ValueError: return '' # Check if this year is between today's year +/- (15, 100) if (1919 <= year <= 2019): # Check if there are other 4 digits before these 4 ones if (len(field[-8 - i:n - i]) == 8): try: f_date = dt.strptime(field[-8 - i:n - i], '%d%m%Y').strftime('%d/%m/%Y') match = True return f_date except ValueError: pass else: return '' i += 1
Takes a sequence of digits as input.
extracts the last four digits from that sequence.
Checks if the extracted four digits are between 2019 and 1919, if not, it breaks.
If yes, it checks if there are more 4 digits before the previously extracted ones, if not it breaks.
If yes, it tries to format the whole 8 digits.
- If there is a ValueError exception, it passes (ValueError, means there are 8 digits, the last four of them represent a correct year, but the fist four digits are wrong. So it passes to increment i + 1 to add a the next digits in the front and remove the last digit in the processed sequence).
- i = 0, match = False
- year = 1946
- test 1 (year between 2019 and 1919): passes.
- test2 (there are 4 other digits before 1946, which are 0320): passes.
- format the whole 8 digits: ValueError exception, so i = i+1 and pass to the next iteration.
- Iteration 2:
- i = 1, match = False
- year = 0194
- test 1 (year between 2019 and 1919): fails, so i = i + 1 and pass to the next iteration.
- Iteration 3:
- i = 2, match = False
- year = 2019
- test 1: passes
- test 2: passes
- format the whole 8 digits (13032019): 13/03/2019 (No ValueError exception) passes
- match = True, return the formatted date, break from the while loop.
This function works fine, but the way it handles the errors seems ugly. Also I believe it is not optimized (same exceptions are repeated, a lot of returns and the code does not seem elegant).
How to reformat the code and make it more optimized?