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Write a Python program to find the dates 30 days after and 7 days before a date.
2026-12-02 2026-10-26
timedelta.from datetime import date, timedelta d = date(2026, 11, 2)print(d + timedelta(days=30), d - timedelta(days=7))2026-12-02 2026-10-26
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Write a Python program to print a date in several formats.
%d-%m-%Y 02-11-2026 %d/%m/%y 02/11/26 %B %d, %Y November 02, 2026 %a %d %b Mon 02 Nov
strftime codes.from datetime import date d = date(2026, 11, 2)for fmt in ["%d-%m-%Y", "%d/%m/%y", "%B %d, %Y", "%a %d %b"]: print(fmt.ljust(10), d.strftime(fmt))%d-%m-%Y 02-11-2026 %d/%m/%y 02/11/26 %B %d, %Y November 02, 2026 %a %d %b Mon 02 Nov
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Write a Python program to convert the string “15/08/2026 09:30” into a datetime.
2026-08-15 09:30:00 Saturday
datetime.strptime(text, format).from datetime import datetime dt = datetime.strptime("15/08/2026 09:30", "%d/%m/%Y %H:%M")print(dt, dt.strftime("%A"))2026-08-15 09:30:00 Saturday
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20 iterator and generator programs: iter() and next(), custom iterator classes, generator functions with yield, generator expressions, infinite sequences, pipelines and itertools.
Read the Iterators and Generators lesson first if the topic is new to you.
iter() and next().Easyfor loop using while, iter() and next().Easyitertools.groupby.EasyWrite a Python program to create a date and print its year, month, day and weekday.
2026-11-02 2026 11 2 Monday
date(y, m, d) and its attributes.from datetime import date d = date(2026, 11, 2)print(d, d.year, d.month, d.day, d.strftime("%A"))2026-11-02 2026 11 2 Monday
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Write a Python program that groups log lines by level with itertools.groupby.
ERROR ['db', 'disk'] INFO ['ok', 'start']
groupby groups consecutive equal keys, so sort first.from itertools import groupby logs = [("ERROR", "db"), ("INFO", "start"), ("ERROR", "disk"), ("INFO", "ok")]for level, group in groupby(sorted(logs), key=lambda x: x[0]): print(level, [msg for _, msg in group])ERROR ['db', 'disk'] INFO ['ok', 'start']
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Write a generator that keeps a running average of values sent to it.
10.0 15.0 30.0
value = yield result receives what send() passes.def averager(): total, count, average = 0, 0, None while True: value = yield average total += value count += 1 average = total / count avg = averager()next(avg) # start the generatorprint(avg.send(10), avg.send(20), avg.send(60))10.0 15.0 30.0
The generator pauses here, hands out the current average and waits for the next value.
The first next() runs the code up to the first yield.
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Write a Python program that takes Fibonacci numbers while they are below 100.
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
itertools.takewhile.from itertools import takewhile def fibonacci(): a, b = 0, 1 while True: yield a a, b = b, a + b print(list(takewhile(lambda n: n < 100, fibonacci())))[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
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Write a Python program that compares the memory of a list and a generator of a million numbers.
True True
sys.getsizeof.import sys as_list = [n for n in range(1_000_000)]as_gen = (n for n in range(1_000_000))print(sys.getsizeof(as_list) > 1_000_000, sys.getsizeof(as_gen) < 1_000)True True
The exact byte counts depend on the Python version, so the program prints comparisons.
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Write a Python program that shows zip and enumerate return iterators.
('a', 1)
[('b', 2), ('c', 3)]
[(1, 'x'), (2, 'y')] []next() on them and see the rest continue.pairs = zip(["a", "b", "c"], [1, 2, 3])print(next(pairs))print(list(pairs))numbered = enumerate(["x", "y"], start=1)print(list(numbered), list(numbered))('a', 1)
[('b', 2), ('c', 3)]
[(1, 'x'), (2, 'y')] []New to this topic? Read the lesson, then come back.