Python is a versatile and powerful programming language that has become a favorite among developers for its simplicity and readability. Whether you're a beginner or an experienced programmer, knowing some of the most useful Python functions can make your coding life easier. In this blog post, we'll explore 20 Python functions that you should know. These functions cover a wide range of applications, from data manipulation to mathematical operations, and will help you write cleaner and more efficient code.
1. print()
The print() function is probably the first function you learned in Python. It outputs the specified message to the console or other standard output device. This function can handle multiple arguments and can be customized with different separators and end characters.
print("Hello, World!")
print("Python", "is", "awesome", sep="-")
print("Hello, World!", end="!!!")2. len()
The len() function returns the number of items in an object. This function works with sequences (like strings, lists, and tuples) and collections (like dictionaries and sets).
my_list = [1, 2, 3, 4]
print(len(my_list))
my_string = "Hello"
print(len(my_string))3. type()
The type() function returns the type of the specified object. This can be useful for debugging or when you need to confirm the data type of a variable.
print(type(5))
print(type(5.0))
print(type("Hello"))
print(type([1, 2, 3]))4. isinstance()
The isinstance() function checks if an object is an instance or subclass of a class or a tuple of classes. This is often used in conditionals to ensure the type of a variable before performing operations on it.
print(isinstance(5, int))
print(isinstance(5.0, float))
print(isinstance("Hello", str))
print(isinstance([1, 2, 3], list))5. abs()
The abs() function returns the absolute value of a number. This is useful for calculations where you need non-negative numbers.
print(abs(-5))
print(abs(5))
print(abs(-3.14))6. sum()
The sum() function adds the items of an iterable (such as a list or tuple) and returns the total. You can also provide a starting value as a second argument.
numbers = [1, 2, 3, 4, 5]
print(sum(numbers))
print(sum(numbers, 10))7. min() and max()
The min() and max() functions return the smallest and largest item in an iterable, respectively. These functions can also take multiple arguments and return the smallest or largest value among them.
numbers = [1, 2, 3, 4, 5]
print(min(numbers))
print(max(numbers))
print(min(1, 2, 3, 4, 5))
print(max(1, 2, 3, 4, 5))8. round()
The round() function rounds a number to a specified number of decimal places. If the number of decimal places is not specified, it rounds to the nearest integer.
print(round(3.14159, 2))
print(round(3.14159, 3))
print(round(3.14159))9. sorted()
The sorted() function returns a new sorted list from the items in an iterable. It does not modify the original iterable. You can also specify the sort order and a custom key function.
numbers = [5, 2, 9, 1, 5, 6]
print(sorted(numbers))
print(sorted(numbers, reverse=True))
words = ["banana", "apple", "cherry"]
print(sorted(words, key=len))10. reversed()
The reversed() function returns an iterator that accesses the given sequence in the reverse order. This can be useful for looping through items in reverse.
numbers = [1, 2, 3, 4, 5]
for num in reversed(numbers):
print(num)11. enumerate()
The enumerate() function adds a counter to an iterable and returns it as an enumerate object. This is useful for getting the index of items in a loop.
words = ["hello", "world", "python"]
for index, word in enumerate(words):
print(index, word)12. zip()
The zip() function takes iterables (can be zero or more), aggregates them in a tuple, and returns it. This is useful for iterating over multiple sequences in parallel.
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
for name, age in zip(names, ages):
print(f"{name} is {age} years old")13. map()
The map() function applies a given function to all items in an iterable and returns a map object (an iterator). This is useful for applying a transformation to all items in a sequence.
def square(x):
return x * x
numbers = [1, 2, 3, 4, 5]
squared_numbers = map(square, numbers)
print(list(squared_numbers))14. filter()
The filter() function constructs an iterator from elements of an iterable for which a function returns true. This is useful for filtering items in a sequence based on a condition.
def is_even(x):
return x % 2 == 0
numbers = [1, 2, 3, 4, 5, 6]
even_numbers = filter(is_even, numbers)
print(list(even_numbers))15. reduce()
The reduce() function from the functools module applies a function of two arguments cumulatively to the items of an iterable, from left to right, to reduce the iterable to a single value. This is useful for performing cumulative operations like summing or multiplying items.
from functools import reduce
def add(x, y):
return x + y
numbers = [1, 2, 3, 4, 5]
total = reduce(add, numbers)
print(total)16. all() and any()
The all() function returns True if all elements of the iterable are true (or if the iterable is empty). The any() function returns True if any element of the iterable is true. These functions are useful for checking conditions in a sequence.
numbers = [1, 2, 3, 4, 5]
print(all(x > 0 for x in numbers))
print(any(x > 4 for x in numbers))17. chr() and ord()
The chr() function returns the string representing a character whose Unicode code point is the integer passed. The ord() function returns an integer representing the Unicode code point of the given character. These functions are useful for working with ASCII and Unicode characters.
print(chr(97))
print(ord('a'))18. bin(), oct(), and hex()
The bin(), oct(), and hex() functions convert an integer to a binary, octal, or hexadecimal string, respectively. These functions are useful for working with different number bases.
print(bin(10))
print(oct(10))
print(hex(10))19. eval()
The eval() function parses the expression passed to it and runs Python expression (code) within the program. This can be useful for dynamically evaluating expressions, but it should be used with caution due to potential security risks.
x = 1
print(eval('x + 1'))20. exec()
The exec() function executes the dynamically created program, which can either be a string or object code. This function is more powerful than eval() as it can execute complex code structures.
code = 'for i in range(5): print(i)'
exec(code)These 20 functions are just a small sample of the powerful tools Python offers. Knowing them will help you write more efficient and readable code. Whether you're manipulating data, performing calculations, or simply iterating through sequences, these functions will make your life as a Python developer easier.
Happy coding!
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