expected two blank lines pep8 warning in python

Question

I'm using vim editor as python IDE. Below is a simple python program to calculate square root of a number:

import cmath
def sqrt():
    try:
        num = int(input("Enter the number : "))
        if num >= 0:
            main(num)
        else:
            complex(num)
    except:
        print("OOPS..!!Something went wrong, try again")
        sqrt()
    return

def main(num):
    squareRoot = num**(1/2)
    print("The square Root of ", num, " is ", squareRoot)
    return

def complex(num):
    ans = cmath.sqrt(num)
    print("The Square root if ", num, " is ", ans)
    return

sqrt()

And the warnings are :

1-square-root.py|2 col 1 C| E302 expected 2 blank lines, found 0 [pep8]
1-square-root.py|15 col 1 C| E302 expected 2 blank lines, found 1 [pep8]
1-square-root.py|21 col 1 C| E302 expected 2 blank lines, found 0 [pep8]

Can you please tell why these warnings are coming?

Answer 1

import cmath


def sqrt():
    try:
        num = int(input("Enter the number : "))
        if num >= 0:
            main(num)
        else:
            complex_num(num)
    except:
        print("OOPS..!!Something went wrong, try again")
        sqrt()
    return


def main(num):
    square_root = num**(1/2)
    print("The square Root of ", num, " is ", square_root)
    return


def complex_num(num):
    ans = cmath.sqrt(num)
    print("The Square root if ", num, " is ", ans)
    return

sqrt()

The previous will fix your PEP8 problems. After your import you need to have 2 new lines before starting your code. Also, between each def foo() you need to have 2 as well.

In your case you had 0 after import, and you had 1 newline between each function. Part of PEP8 you need to have a newline after the end of your code. Unfortunately I don't know how to show it when I paste your code in here.

Pay attention to the naming, it's part of PEP8 as well. I changed complex to complex_num to prevent confusion with builtin complex.

In the end, they're only warning, they can be ignored if needed.

Answer 2

with warnings:-  
import math  
def my():  
    print("hello world")  
my()

Without warnings:-  
import math 


def my():  
    print("hello world")  
my()

Here if you see the two lines space after import statement for second code snippet which will not give any warnings. Again if you are writing two methods definition you have two give two lines as space between your code block.

Answer 3

Here is the link to the documentation: PEP8 Style Guide for Python
You should add two spaces between the functions, as shown below:

import cmath


def sqrt():
    try:
        num = int(input("Enter the number : "))
        if num >= 0:
            main(num)
        else:
            complex_num(num)
    except:
        print("OOPS..!!Something went wrong, try again")
        sqrt()
    return


def main(num):
    square_root = num ** (1 / 2)
    print("The square Root of ", num, " is ", square_root)
    return


def complex_num(num):
    ans = cmath.sqrt(num)
    print("The Square root if ", num, " is ", ans)
    return


sqrt()