Python Functions and Tricks Cheat Sheet

Python cheat sheets are the 80/20 principle applied to coding: learn 80% of the language features in 20% of the time.
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Try It Yourself:

Exercise: Modify each function and play with the output!

Here’s the code for copy&paste:

# 1. map(func, iter)
m = map(lambda x: x[0], ['red', 'green', 'blue'])
print(list(m))
# ['r', 'g', 'b']


# 2. map(func, i1, ...,ik)
l1 = [0, 2, 2]
l2 = ['apple', 'orange', 'banana']
m = map(lambda x, y: str(x) + ' ' + str(y) + 's', l1, l2)
print(list(m))
# ['0 apples', '2 oranges', '2 bananas']


# 3. string.join(iter)
print(' marries '.join(['Alice', 'Bob']))
# Alice marries Bob


# 4. filter(func, iterable)
print(list(filter(lambda x: x>17, [1, 15, 17, 18])))
# [18]


# 5. string.strip()
print("    \n   \t  42  \t ".strip())
# 42


# 6. sorted(iter)
print(sorted([8, 3, 2, 42, 5]))
# [2, 3, 5, 8, 42]


# 7. sorted(iter, key=key)
print(sorted([8, 3, 2, 42, 5], key=lambda x: 0 if x==42 else x))
# [42, 2, 3, 5, 8]


# 8. help(func)
help(str.upper)
'''
Help on method_descriptor:

upper(self, /)
    Return a copy of the string converted to uppercase.
'''


# 9. zip(i1, i2, ...)
print(list(zip(['Alice', 'Anna'], ['Bob', 'Jon', 'Frank'])))
# [('Alice', 'Bob'), ('Anna', 'Jon')]


# 10. Unzip
print(list(zip(*[('Alice', 'Bob'), ('Anna', 'Jon')])))
# [('Alice', 'Anna'), ('Bob', 'Jon')]


# 11. Enumerate
print(list(enumerate(['Alice', 'Bob', 'Jon'])))
# [(0, 'Alice'), (1, 'Bob'), (2, 'Jon')]

The following tutorials address those functions in great detail (including videos on the most important functions).

Related Articles:

• Map Function
• String Join
• Filtering Lists
• Strip and Trim
• Python Sorting
• Zip and Unzip

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Chris

While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students.

To help students reach higher levels of Python success, he founded the programming education website Finxter.com. He’s author of the popular programming book Python One-Liners (NoStarch 2020), coauthor of the Coffee Break Python series of self-published books, computer science enthusiast, freelancer, and owner of one of the top 10 largest Python blogs worldwide.

His passions are writing, reading, and coding. But his greatest passion is to serve aspiring coders through Finxter and help them to boost their skills. You can join his free email academy here.