# Palindrome-inize a number

For example if I start with the number 146. I first reverse it, so it becomes 641. Then I add this to the original number to make 787 which is a palindrome. I would repeat the process if the answer is not a palindrome.

I made this program show how long it ran for when it finishes or is interrupted and also to write the output to a file called output.txt.

from sys import exit
from signal import SIGINT, signal
from timeit import default_timer

def n(x):

counter = 0
b = 0
start = default_timer()

def t(*args):

end = default_timer()
total = end - start
print (total)

with open('output.txt','w') as f:

f.write('{}\n{}\n{}'.format(b, counter, total))

exit(0)

signal(SIGINT,t)

while True:

b += int(str(x)[::-1])

if b == int(str(b)[::-1]):

end = default_timer()
print (b, counter)
t()
break

else:

counter += 1
print (b,counter)
x = b

• First improvement I'd suggest is to use decent names for variables and methods, add comments, and skip fewer lines. Commented Jul 28, 2016 at 13:53
• @BusyAnt I just realised that I pasted the wrong version of my code. The only thing different is that the newer one has more sensible variable names but still doesn't have comments/less blank lines. Thanks for pointing that out! Commented Jul 28, 2016 at 13:58

A few notes:

• A more pythonic way to determine if a given value is a palindrome:

str(n) == str(n)[::-1]


You do something similar in your code, but are converting from a string back to an int. This is more readable to me.

However, this can slow down the code if we do this sort of casting a lot, so it would be better to abstract this functionality to a loop to reduce the number of casts and further increase readablity:

def is_palindrome(num):
string = str(num)
return string == string[::-1]

• Use the palindrome test as a check with the while loop

• In the while loop, use the logic you already have to add on a reversed int:

n += int(str(n)[::-1])

• I would make it easier to input a number for the code to use, I did this with argparse.

def get_args():
parser = argparse.ArgumentParser(description=
'Generate palindrome from number when added to its reverse')
parser.add_argument('num', type=int, help='number for palindrome generator')
return parser.parse_args()

• Right now you are writing just a snippet of data to a file, but it is being overwritten every time. I'd recommend just outputting to stdout with this current method, or changing it so you append to a file instead of overwrite it. I've gone with the former recommendation in my final code.

• For profiling and timing code, it's recommended you use a Python profiler instead of writing code yourself.

### Final Code

import argparse

def get_args():
parser = argparse.ArgumentParser(description=
'Generate palindrome from number when added to its reverse')
parser.add_argument('num', type=int, help='number for palindrome generator')
return parser.parse_args()

def is_palindrome(num):
string = str(num)
return string == string[::-1]

def main():
args = get_args()
while not is_palindrome(args.num):
args.num += int(str(args.num)[::-1])

return args.num

if __name__ == "__main__":
print(main())


Test run:

\$ python test.py 146
787