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?

I didn't realize PEP8 enforced this. It's kind of gross to require 2 blank lines imo. — Mateen Ulhaq, Feb 10 '19 at 07:53

score 40 · Accepted Answer · answered Nov 01 '15 at 21:06

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.

score 3 · Answer 2 · edited Feb 27 '19 at 17:44

3

You need to give two blank lines between meaningful code blocks.

These include (for example):

The import block
Each function

edited Feb 27 '19 at 17:44

8bitjunkie

12,793
9
57
70

answered Aug 09 '17 at 09:59

Balaji Wanole

49
3

Can you provide a sample to visualize what you are saying? – Noel Widmer Aug 09 '17 at 10:22

Lakshmikant Deshpande · Answer 3 · 2019-07-09T07:09:30.017

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()

You should provide a small snippet or syntax of how to write that. — , Aug 09 '17 at 10:31

Balaji Wanole · Answer 4 · 2017-08-09T11:50:06.853

1

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.

edited Aug 09 '17 at 11:50

answered Aug 09 '17 at 11:24

Balaji Wanole

49
3

score 1 · Answer 5 · answered Mar 08 '18 at 09:48

All answers seem to be correct. To avoid doing this by hand, you can also use the autopep8 package (pip install autopep8). The result of calling autopep8 filename.py is the same:

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()

PS: have a look at if __name__ == "__main__":

expected two blank lines pep8 warning in python

5 Answers5

Linked