Skip to content

Latest commit

 

History

History
284 lines (193 loc) · 4.83 KB

09-built-in-functions.md

File metadata and controls

284 lines (193 loc) · 4.83 KB

7 Python Built-in Functions You Should Know

Video Link: https://youtu.be/2_xfAoJFWBY

In this video, we will look at seven different Python Built-in functions that will help you write more pythonic code.

Python all() and any()

Code For any()

boolean_list = [True,True]
print(all(boolean_list))

Output

True

Change second element to False.

boolean_list = [True,False]
print(all(boolean_list))

Output

False

Code for all()

boolean_list = [True,False]
print(any(boolean_list))

Output

True

Program to check if a list has all odd numbers

numbers = [1,3,5,7,9]
all_odd = all([n%2 for n in numbers])
print(all_odd)

Output

True

Python enumerate()

First Program

name_list = ['Mary', 'Anna', 'Alexandra']
marks_list = [70, 45, 96]

counter = 0
for student in name_list:
    if student == "Anna":
        print(marks_list[counter])
        break
    counter += 1

Output

45

Same program using enumerate()

name_list = ['Mary', 'Anna', 'Alexandra']
marks_list = [70, 45, 96]

for counter, student in enumerate(name_list):
    if student == "Anna":
        print(marks_list[counter])
        break

Output

45

Python zip()

Group the corresponding elements of two lists.

number_list = [1, 2, 3]
str_list = ['one', 'two', 'three']

result = zip(number_list, str_list)
print(list(result))

Output

[(1, 'one'), (2, 'two'), (3, 'three')]

Use zip() instead of enumerate() in earlier code

name_list = ['Mary', 'Anna', 'Alexandra']
marks_list = [70, 45, 96]

for student, marks in zip(name_list, marks_list):
    if student == "Anna":
        print(marks)
        break

Output

45

PythoN dir()

Returns all the attributes and methods present inside list

numbers_list = [1, 2]
print(dir(numbers_list))

Output

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

List out all definition of math module

import math

print(dir(math))

Output

['__doc__', '__loader__', '__name__', '__package__', '__spec__', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'comb', 'copysign', 'cos', 'cosh', 'degrees', 'dist', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'isnan', 'isqrt', 'ldexp', 'lgamma', 'log', 'log10', 'log1p', 'log2', 'modf', 'nan', 'perm', 'pi', 'pow', 'prod', 'radians', 'remainder', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'tau', 'trunc']

Python eval()

Runs the string passed as python expression

x = 1
print(eval('x + 1'))

Output

2

Create command line calculator

while True:
    print(eval(input(">>> ")))

Output

4 + 5
9

Python map()

Create a new list with squared numbers from the original list

numbers = [1, 2, 3, 4, 5]

squared_nums = []

square = lambda n: n**2

for num in numbers:
    squared_nums.append(square(num))

print(squared_nums)

Output

[1, 4, 9, 16, 25]

Solve the same problem using map()

numbers = [1, 2, 3, 4, 5]

squared_nums = map(lambda n: n ** 2, numbers)
print(list(squared_nums))

Output

[1, 4, 9, 16, 25]

Python filter()

Filter out even numbers from the list using filter()

numbers = [234, 3245 ,639, 550, 654]

even_numbers = list(filter(lambda n: n % 2 ==0, numbers))
print(even_numbers)

Output

[234, 550, 654]

Things to Take Away from this video

  • all() - returns True if all elements of an iterable are True
  • any() - returns True if any element of the iterable is True
  • enumerate() - adds counter to an iterable and returns it
  • zip() - aggregrates elements of multiple iterables into tuples
  • dir() - returns all attributes and methods of an object
  • eval() - runs the string passed to it as a python expression
  • map() - applies a given function to each element of an iterable
  • filter() - filters out only the element for which the function returns True