Master Python Date Parsing: From dateparser to Arrow for Complex Time Ranges

Python's standard time and datetime modules cover most everyday scenarios, but they struggle with unusual date formats. For those cases, third‑party libraries such as DateParser and Dateutil can convert arbitrary strings into standard timestamps.

DateParser and Dateutil handle many quirky formats. Example:

# -*- coding: utf-8 -*-
# @Time : 2020-12-05 16:46
import time
import dateparser
from dateutil import parser

print(dateparser.parse("2020/11/7 5:01:08"))
print(parser.parse("2020"))

When exporting large datasets, platforms often limit the amount of data per request. To avoid failures, it is useful to split the export period into smaller intervals (e.g., monthly or weekly).

While searching for Python tools to split time ranges, the Arrow library stands out. Arrow wraps datetime and provides a fluent API for manipulation and range generation.

Basic Arrow usage examples:

# -*- coding: utf-8 -*-
# @Time : 2020-12-05 16:46
i = arrow.now()

# i.replace(day=1)   # set day to 1
# i.shift(months=-1) # go back one month
# i.format('YYYY-MM-DD') # format output
print(i.shift(days=-30).format('YYYY-MM-DD'))
print(i.shift(months=-3).format('YYYY-MM-DD'))
print(i.replace(day=1).shift(months=-1).format('YYYY-MM-DD'))
print(i.replace(day=1).shift(months=-1).format('YYYY-MM-DD HH:mm:ss'))

Arrow also offers span_range and range methods to generate sequences of dates with a chosen granularity. The following functions illustrate how to obtain monthly, weekly, or custom formatted ranges over a 120‑day period:

# -*- coding: utf-8 -*-
# @Time : 2020-12-05 16:46
import arrow
import datetime

end = datetime.datetime.now()
start = end + datetime.timedelta(days=-120)

def timeYmdRange(start=start, end=end):
    tRange = []
    for r in arrow.Arrow.span_range('months', start, end):
        qTime = [i.format('YYYY-MM-DD') for i in r]
        tRange.append(qTime)
    return tRange

def timeWeekRange(start=start, end=end):
    tRange = []
    for r in arrow.Arrow.span_range('weeks', start, end):
        qTime = [i.format('YYYY-MM-DD') for i in r]
        tRange.append(qTime)
    return tRange

def timeMonthRange(start=start, end=end):
    tRange = []
    for r in arrow.Arrow.range('months', start, end):
        qTime = r.format('YYYYMM')
        tRange.append(qTime)
    return tRange

print(timeWeekRange())

Using Arrow's range capabilities satisfies the need for precise time slicing without resorting to multiple complex libraries, keeping the solution simple and maintainable.