Python Practice Problems

Python practice problems help beginners to become experts in a python programming language with a small amount of practice effort.

Records with namedtuple

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Python Practice › Collections Programs › Program 13

Records with namedtuple

EasyCollections Programs · 13 of 20

Write a Python program to store employee records as named tuples.

Output
Asha QA 52000
Ravi Dev 61000
Ravi

Approach

  1. namedtuple("Employee", [...]).

Solution

Python
from collections import namedtuple Employee = namedtuple("Employee", ["name", "dept", "salary"])staff = [Employee("Asha", "QA", 52000), Employee("Ravi", "Dev", 61000)]for e in staff:    print(e.name, e.dept, e.salary)print(max(staff, key=lambda e: e.salary).name)
Output
Asha QA 52000
Ravi Dev 61000
Ravi

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Moving average with deque

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Python Practice › Collections Programs › Program 11

Moving average with deque

MediumCollections Programs · 11 of 20

Write a Python program to compute a moving average over a window of 3 values.

Output
[20.0, 30.0, 40.0]

Approach

  1. Keep the window in a deque with maxlen and average it each step.

Solution

Python
from collections import deque values = [10, 20, 30, 40, 50]window = deque(maxlen=3)averages = []for v in values:    window.append(v)    if len(window) == 3:        averages.append(sum(window) / 3)print(averages)
Output
[20.0, 30.0, 40.0]

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Rotate a deque

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Python Practice › Collections Programs › Program 12

Rotate a deque

EasyCollections Programs · 12 of 20

Write a Python program to rotate a list of players for a round-robin game.

Output
1 ['A', 'B', 'C', 'D']
2 ['B', 'C', 'D', 'A']
3 ['C', 'D', 'A', 'B']

Approach

  1. rotate(n) moves items from the end to the front.

Solution

Python
from collections import deque players = deque(["A", "B", "C", "D"])for round_no in range(1, 4):    print(round_no, list(players))    players.rotate(-1)
Output
1 ['A', 'B', 'C', 'D']
2 ['B', 'C', 'D', 'A']
3 ['C', 'D', 'A', 'B']

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More collections programs

#13EasyRecords with namedtuple#14Easynamedtuple helpers#15MediumLRU cache with OrderedDict#16EasyLayered settings with ChainMap

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Keep the last N items

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Python Practice › Collections Programs › Program 10

Keep the last N items

EasyCollections Programs · 10 of 20

Write a Python program that keeps only the 3 most recent log lines.

Output
['log 4', 'log 5', 'log 6']

Approach

  1. deque(maxlen=3) drops the oldest automatically.

Solution

Python
from collections import deque recent = deque(maxlen=3)for i in range(1, 7):    recent.append(f"log {i}")print(list(recent))
Output
['log 4', 'log 5', 'log 6']

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#11MediumMoving average with deque#12EasyRotate a deque#13EasyRecords with namedtuple#14Easynamedtuple helpers

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Stack with deque

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Python Practice › Collections Programs › Program 9

Stack with deque

EasyCollections Programs · 9 of 20

Write a Python program that uses a deque as a last-in, first-out stack.

Output
back to product -> search

Approach

  1. append and pop from the same end.

Solution

Python
from collections import deque history = deque()for page in ["home", "search", "product"]:    history.append(page)print("back to", history.pop(), "->", history[-1])
Output
back to product -> search

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More collections programs

#10EasyKeep the last N items#11MediumMoving average with deque#12EasyRotate a deque#13EasyRecords with namedtuple

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Queue with deque

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Python Practice › Collections Programs › Program 8

Queue with deque

EasyCollections Programs · 8 of 20

Write a Python program that uses a deque as a first-in, first-out queue.

Output
serving Asha | waiting: ['Ravi', 'Meena']
serving Ravi | waiting: ['Meena']
serving Meena | waiting: []

Approach

  1. append to join, popleft to serve.

Solution

Python
from collections import deque queue = deque()for customer in ["Asha", "Ravi", "Meena"]:    queue.append(customer)while queue:    print("serving", queue.popleft(), "| waiting:", list(queue))
Output
serving Asha | waiting: ['Ravi', 'Meena']
serving Ravi | waiting: ['Meena']
serving Meena | waiting: []

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Count with defaultdict(int)

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Python Practice › Collections Programs › Program 6

Count with defaultdict(int)

EasyCollections Programs · 6 of 20

Write a Python program to count characters with defaultdict(int).

Output
{'b': 1, 'a': 3, 'n': 2}

Approach

  1. Missing keys start at 0.

Solution

Python
from collections import defaultdict counts = defaultdict(int)for ch in "banana":    counts[ch] += 1print(dict(counts))
Output
{'b': 1, 'a': 3, 'n': 2}

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Unique values per key

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Python Practice › Collections Programs › Program 7

Unique values per key

EasyCollections Programs · 7 of 20

Write a Python program that collects the unique cities each customer ordered from.

Output
{'asha': ['Mumbai', 'Pune'], 'ravi': ['Delhi']}

Approach

  1. defaultdict(set).

Solution

Python
from collections import defaultdict orders = [("asha", "Pune"), ("ravi", "Delhi"), ("asha", "Mumbai"), ("asha", "Pune")]cities = defaultdict(set)for customer, city in orders:    cities[customer].add(city)print({k: sorted(v) for k, v in cities.items()})
Output
{'asha': ['Mumbai', 'Pune'], 'ravi': ['Delhi']}

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More collections programs

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Group words by first letter

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Python Practice › Collections Programs › Program 5

Group words by first letter

EasyCollections Programs · 5 of 20

Write a Python program to group words by their first letter with defaultdict.

Output
{'a': ['apple', 'avocado'], 'b': ['banana', 'blueberry'], 'c': ['cherry']}

Approach

  1. defaultdict(list).

Solution

Python
from collections import defaultdict words = ["apple", "avocado", "banana", "blueberry", "cherry"]groups = defaultdict(list)for w in words:    groups[w[0]].append(w)print(dict(groups))
Output
{'a': ['apple', 'avocado'], 'b': ['banana', 'blueberry'], 'c': ['cherry']}

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More collections programs

#6EasyCount with defaultdict(int)#7EasyUnique values per key#8EasyQueue with deque#9EasyStack with deque

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Anagram check with Counter

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Python Practice › Collections Programs › Program 3

Anagram check with Counter

EasyCollections Programs · 3 of 20

Write a Python program to check whether two words are anagrams using Counter.

Output
listen silent True
python typhon True
apple apply False

Approach

  1. Equal letter counts mean anagrams.

Solution

Python
from collections import Counter for a, b in [("listen", "silent"), ("python", "typhon"), ("apple", "apply")]:    print(a, b, Counter(a) == Counter(b))
Output
listen silent True
python typhon True
apple apply False

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