Returning in for loops python

Question

I've been trying a while now but i just can't seem to get it right. I'm a starting programmer and have to do an assignment for school. The program should ask the user for a number and print a diamond shape, based on this number. Now I've got it working fine.. but I have print statements outside my main. How do i get this inside my main?

my code:

def loop(start, eind, step, ei):
    for a in range (start, eind, step):       
        for b in range(a):                  
            print(" ", end="")                
        for c in range(ei+1, a, -1):
            print(a, end="")            
        for d in range(a, ei):           
            print(a, end="")             
    print("")  

def main():
    print("Welcome!  :) ")
    loop(y,0,-1,y)
    loop(2,y+1,1,y)

Hope you guys can help me out! By the way, I've got more code for this program but that's not relevant (like asking the user for "y").

*but I have print statements outside my main. How do i get this inside my main?* what do you mean by that? — Leb, Oct 02 '15 at 15:16

Anand S Kumar · Accepted Answer · 2015-10-02T15:32:02.750

Assuming the indentation you have pasted is correct (and y variable is defined in global scope), your current code does not produce a diamond shape , it would only get produced correctly if the last print("") inside the loop() function was indented inside the for loop.

Given that, what you may want to look into is generator functions with yield statements . Example -

def loop(start, eind, step, ei):
    for a in range (start, eind, step):       
        for b in range(a):                  
            yield " "                
        for c in range(ei+1, a, -1):
            yield a            
        for d in range(a, ei):           
            yield a
        yield '\n'

def main():
    print("Welcome!  :) ")
    for x in loop(y,0,-1,y):
        print(x,end="")
    for x in loop(2,y+1,1,y):
        print(x,end="")

This assumes y variable is defined in global scope.

Demo -

>>> def loop(start, eind, step, ei):
...     for a in range (start, eind, step):
...         for b in range(a):
...             yield " "
...         for c in range(ei+1, a, -1):
...             yield a
...         for d in range(a, ei):
...             yield a
...         yield '\n'
...
>>> def main():
...     print("Welcome!  :) ")
...     y = 5
...     for x in loop(y,0,-1,y):
...         print(x,end="")
...     for x in loop(2,y+1,1,y):
...         print(x,end="")
...
...
>>> main()
Welcome!  :)
     5
    444
   33333
  2222222
 111111111
  2222222
   33333
    444
     5

You might look into the string format() method to make the print statements easier to follow and extend. [Here's an example for a similar question about printing pyramids.](http://stackoverflow.com/a/32427982/2125392) Though that may be beside the point, since the problem seems designed to learn about looping. — CivFan, Oct 02 '15 at 16:10

Returning in for loops python

1 Answers1