Python Practice Problems

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

Memory size of a dictionary

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Python Practice › Dictionary Programs › Program 17

Memory size of a dictionary

EasyDictionary Programs · 17 of 94

Write a Python program to get the memory size of a dictionary with sys.getsizeof, and its number of items.

Input
{"name": "virat", "sport": "cricket"}
Output
2 items
True | bytes on this Python: 184

Approach

  1. sys.getsizeof gives the size of the dict object itself, len the item count.

Solution

Python
import sys d = {"name": "virat", "sport": "cricket"}print(len(d), "items")print(sys.getsizeof(d) > 0, "| bytes on this Python:", sys.getsizeof(d))
Output
2 items
True | bytes on this Python: 184
Note

The byte count depends on the Python version and platform, and it does not include the keys and values themselves.

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More dictionary programs

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Sum of dictionary values

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Python Practice › Dictionary Programs › Program 16

Sum of dictionary values

EasyDictionary Programs · 16 of 94

Write a Python program to add up all the values of a dictionary.

Input
{"x": 23, "y": 10, "z": 7}
Output
40

Approach

  1. sum(d.values()).

Solution

Python
print(sum({"x": 23, "y": 10, "z": 7}.values()))
Output
40

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More dictionary programs

#17EasyMemory size of a dictionary#18EasyDoes a key exist?#19EasyIterate over a dictionary#20EasyDictionary of cubes

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Swap the values of two keys

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Python Practice › Dictionary Programs › Program 15

Swap the values of two keys

EasyDictionary Programs · 15 of 94

Write a Python program to swap the values of two keys.

Input
{"name": "yash", "city": "pune"}
Output
{'name': 'pune', 'city': 'yash'}

Approach

  1. Tuple assignment on the two keys.

Solution

Python
d = {"name": "yash", "city": "pune"}d["name"], d["city"] = d["city"], d["name"]print(d)
Output
{'name': 'pune', 'city': 'yash'}

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More dictionary programs

#16EasySum of dictionary values#17EasyMemory size of a dictionary#18EasyDoes a key exist?#19EasyIterate over a dictionary

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Merge two dictionaries with **

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Python Practice › Dictionary Programs › Program 14

Merge two dictionaries with **

EasyDictionary Programs · 14 of 94

Write a Python program to concatenate two dictionaries using unpacking.

Input
{"name": "yash", "city": "pune"}, {"course": "python", "institute": "sqatools"}
Output
{'name': 'yash', 'city': 'pune', 'course': 'python', 'institute': 'sqatools'}

Approach

  1. {d1, d2} works on all Python 3 versions.

Solution

Python
d1 = {"name": "yash", "city": "pune"}d2 = {"course": "python", "institute": "sqatools"}print({**d1, **d2})
Output
{'name': 'yash', 'city': 'pune', 'course': 'python', 'institute': 'sqatools'}

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More dictionary programs

#15EasySwap the values of two keys#16EasySum of dictionary values#17EasyMemory size of a dictionary#18EasyDoes a key exist?

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Add a key

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Python Practice › Dictionary Programs › Program 13

Add a key

EasyDictionary Programs · 13 of 94

Write a Python program to add a key to a dictionary.

Input
{1: "a", 2: "b"}
Output
{1: 'a', 2: 'b', 3: 'c'}

Approach

  1. Assign to the new key.

Solution

Python
d = {1: "a", 2: "b"}d[3] = "c"print(d)
Output
{1: 'a', 2: 'b', 3: 'c'}

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More dictionary programs

#14EasyMerge two dictionaries with **#15EasySwap the values of two keys#16EasySum of dictionary values#17EasyMemory size of a dictionary

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Sort a dictionary by value

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Python Practice › Dictionary Programs › Program 12

Sort a dictionary by value

EasyDictionary Programs · 12 of 94

Write a Python program to sort a dictionary by its values.

Input
{"d": 14, "b": 52, "a": 13, "c": 1}
Output
[('c', 1), ('a', 13), ('d', 14), ('b', 52)]
{'b': 52, 'd': 14, 'a': 13, 'c': 1}

Approach

  1. key=lambda kv: kv[1].

Solution

Python
d = {"d": 14, "b": 52, "a": 13, "c": 1}print(sorted(d.items(), key=lambda kv: kv[1]))print(dict(sorted(d.items(), key=lambda kv: kv[1], reverse=True)))
Output
[('c', 1), ('a', 13), ('d', 14), ('b', 52)]
{'b': 52, 'd': 14, 'a': 13, 'c': 1}

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More dictionary programs

#13EasyAdd a key#14EasyMerge two dictionaries with **#15EasySwap the values of two keys#16EasySum of dictionary values

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Sort a dictionary by key

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Python Practice › Dictionary Programs › Program 11

Sort a dictionary by key

EasyDictionary Programs · 11 of 94

Write a Python program to sort a dictionary by its keys.

Input
{"d": 21, "b": 53, "a": 13, "c": 41}
Output
('a', 13)
('b', 53)
('c', 41)
('d', 21)
{'a': 13, 'b': 53, 'c': 41, 'd': 21}

Approach

  1. sorted(d.items()) sorts the pairs by key.

Solution

Python
d = {"d": 21, "b": 53, "a": 13, "c": 41}for pair in sorted(d.items()):    print(pair)print(dict(sorted(d.items())))
Output
('a', 13)
('b', 53)
('c', 41)
('d', 21)
{'a': 13, 'b': 53, 'c': 41, 'd': 21}

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More dictionary programs

#12EasySort a dictionary by value#13EasyAdd a key#14EasyMerge two dictionaries with **#15EasySwap the values of two keys

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Character counts of a string

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Python Practice › Dictionary Programs › Program 10

Character counts of a string

EasyDictionary Programs · 10 of 94

Write a Python program to build a dictionary of character counts from a string.

Input
"SQATools"
Output
{'S': 1, 'Q': 1, 'A': 1, 'T': 1, 'o': 2, 'l': 1, 's': 1}

Approach

  1. get(ch, 0) + 1 for each character.

Solution

Python
text = "SQATools"counts = {}for ch in text:    counts[ch] = counts.get(ch, 0) + 1print(counts)
Output
{'S': 1, 'Q': 1, 'A': 1, 'T': 1, 'o': 2, 'l': 1, 's': 1}

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More dictionary programs

#11EasySort a dictionary by key#12EasySort a dictionary by value#13EasyAdd a key#14EasyMerge two dictionaries with **

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Remove duplicate values

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Python Practice › Dictionary Programs › Program 9

Remove duplicate values

EasyDictionary Programs · 9 of 94

Write a Python program to keep only the first key for each distinct value.

Input
{"a": 12, "b": 2, "c": 12, "d": 5, "e": 35, "f": 5}
Output
{'a': 12, 'b': 2, 'd': 5, 'e': 35}

Approach

  1. Remember the values seen while copying items.

Solution

Python
d = {"a": 12, "b": 2, "c": 12, "d": 5, "e": 35, "f": 5}seen = set()result = {}for k, v in d.items():    if v not in seen:        seen.add(v)        result[k] = vprint(result)
Output
{'a': 12, 'b': 2, 'd': 5, 'e': 35}

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More dictionary programs

#10EasyCharacter counts of a string#11EasySort a dictionary by key#12EasySort a dictionary by value#13EasyAdd a key

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Clear a dictionary

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Python Practice › Dictionary Programs › Program 8

Clear a dictionary

EasyDictionary Programs · 8 of 94

Write a Python program to remove all items from a dictionary.

Input
{"a": 1, "b": 2}
Output
{} {}

Approach

  1. clear() empties the same object.

Solution

Python
d = {"a": 1, "b": 2}alias = dd.clear()print(d, alias)
Output
{} {}

Line by line

Line 3

clear empties the dict itself, so every name pointing to it sees the change. d = {} would only rebind d.

Learn the concept

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More dictionary programs

#9EasyRemove duplicate values#10EasyCharacter counts of a string#11EasySort a dictionary by key#12EasySort a dictionary by value

← All 94 Dictionary Programs