Printing a rectangle

Question

I have an assignment as follows:

Write a program which reads from the keyboard two integers n and m, and a character c from the keyboard. This program should define and call a function: print rectangle(n, m, c) which prints a rectangle of size n x m consisting of the character c

My solution is:

n=int(input("Enter the lenght of the rectangle: "))
m=int(input("Enter the width: "))
c="c"
def print_rect(n, m, c):
    for a in range(m):
        print (n*c)
print_rect(n, m, c)
input("Press enter to close")

I am sure there are alternative ways to do this assignment. How would you code this assignment? Do you think my solution is OK?

Answer 1

I think the assignment wants you to read the character from input as well.

When you are printing the input you are composing the string m times. More optimal solution is if you do that 1 time and output it m times:

def print_rect(n, m, c):
    row=n*c
    for a in range(m):
        print (row)

I would even do it with this oneliner:

print((n * c + '\n') * m, end="")

Answer 2

1. It makes little sense to have a variable c that always contains 'c'. Simply replace c by 'c' in your print call.
2. Learn about PEP8 and about checking that your code conforms to PEP8. A few things to check here:
   1. spaces between = when doing an assignment
   2. new lines between function definitions
3. no space after print: print(n * c) or print n * c (the former is better since it's Python 3 proof)
4. Error checking! What happens if I enter anything else than a number? It's possibly not required by your assignment, but be aware that it can cause issues.

Answer 3

def print_rect(n, m, c):
    l = (n * c for a in range(m))
    print '\n'.join(l)

I believe this would be slightly faster. I did a test on my computer:) (I'm using Python 2.7.5 so the code is slightly different with Python3)

import timeit
prep = """
n = 10
m = 7
c = 'D'
"""

old = """
    for a in xrange(m):
        print n * c
        """

new = """
    l = (n * c for a in xrange(m))
    print \'\\n\'.join(l)
    """



print 'Old'
print timeit.timeit(old, setup=prep, number=10)

print 'New'
print timeit.timeit(new, setup=prep, number=10)

The new implementation is like 10 times faster:)

Answer 4

Here is my implementation for printing hollow rectangles:

import sys

# Python 2/3 compatibility shims
if sys.hexversion >= 0x3000000:
    inp = input
    rng = range
else:
    inp = raw_input
    rng = xrange

def get_int(prompt):
    while True:
        try:
            return int(inp(prompt))
        except ValueError:
            pass

def get_ch(prompt):
    while True:
        res = inp(prompt).strip()
        if res:
            return res[:1]

def make_row(w, edge, center):
    return edge*(w>0) + center*(w-2) + edge*(w>1)

def print_rectangle(h, w, c):
    top_row = make_row(w, c, c)
    mid_row = make_row(w, c, ' ')
    rows = [top_row]*(h>0) + [mid_row]*(h-2) + [top_row]*(h>1)
    print('\n'.join(rows))

def main():
    h = get_int('Rectangle height: ')
    w = get_int('Rectangle width: ')
    c = get_ch('Character to use: ')
    print_rectangle(h, w, c)

if __name__=="__main__":
    main()

which runs like:

Rectangle height: 4
Rectangle width: 6
Character to use: F
FFFFFF
F    F
F    F
FFFFFF