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?

• Max: "[...] and a character c from the keyboard". c should also be input from the user, just like n and m.
• Max: Should the rectangle be solid or should you only print the outline? If it can be solid you would only need to change what I said about the character.
• Rakanoth: Thank you. The rectangle should be solid. But you said something important. What should I do if I only want to print the outline?
• Max: I don't have any code of it but I'd made a nested loop over the width and the length of the rectangle and calculate the position of the outline and only print the character when the loop hits that value. Hope I made it clear.

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:)

• Max: n, m, and c, needs to be inputs (but I guess OP can easily modify that:))
• Quentin Pradet: Upvoted because it's an interesting find. But it's also kind of a hack: I would argue it's harder to read, which is way more important than speed.
• shengy: I recommend python.net/~goodger/projects/pycon/2007/idiomatic/handout.html where I got this idea:)
• Malachi: I ran your code in IDLE and it doesn't make a rectangle.
• Thomas Junk: »I ran your code in IDLE and it doesn't make a rectangle« that is then a creative solution ;)

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