Many times to represent the data or display it on the output console, we need to pad a number with extra zeros to make it looks consistent.
In this post, I a going to share the simplest two methods for Python padding.
Before jumping into the code, let’s see…
If you have the serial number from 0 to 999. It looks something like this…
0 1 2 . . 8 9 . . 25 26 17 . . 997 998 999
The number series does not look fancy as the length of the number in the series varies. If we pad the number to make it have the same length (says 3), it looks like this…
If we pad the number to make it have the same length (says 3), it looks like this…
000 001 002 . . 008 009 . . 025 026 017 . . 997 998 999
From the above two number series list, which one does look good?
I am sure, it’s Second!
So let’s see how to pad integer number and string in Python.
There are multiple methods of doing this. Let’s check some of the simple Python tricks…
strNum = '7' print strNum.zfill(3)
The zfill is a function associated with the string object. 3 is the expected length of the string after padding.
strNum = '7' strNum.rjust(3, '0')
The rjust() is string inbuilt function in Python. Pass the expected length of the string after padding and character to be used for padding as two parameters of the function.
With this function, you can use any character for padding.
Both the method will give the same output as…
“1” gives out as a string of “001”
“2” gives “002”, “99” gives “099”, “100” gives “100”, “999” gives “999”
Exception: If the length of the given string is greater than the padding length, it returns the same string.
Above code returns “7000” for “7000” even if you pass 3 as expected length after padding.
In Python, you can not pad the integer number. You have to convert the number into the string. And then pad it.
Conversion of the integer into the string is very easy.
num = 7 strNum = str(num)
Now you can make the consistent length for all the numbers in series.
This function will be more helpful if you have a function that manipulates the same length of the input string.
Other Python Tricks:
This is all about Python padding. There are so many other methods of doing this. To make it simple to use in your code, I have listed the simplest two methods.
If you think as there are other simplest ways of solving this problem, comment below. I am sure it will be helpful other Python Programmers.
I am a Python enthusiast who loves Linux and Vim. I hold a Master of Computer Science degree from NIT Trichy and have 10 years of experience in the IT industry, focusing on the Software Development Lifecycle from Requirements Gathering, Design, Development to Deployment. I have worked at IBM, Ericsson, and NetApp, and I share my knowledge on CSEstack.org.
Hi Aniruddha, padding is a cute thing, thanks! Any ideas on how to do the reverse thing as easy as it is with padding?
I mean geeting back integers from padded strings.
Hey Kęstutis, Glad to see you here! There is no padding for integer values in Python. So, when you convert the number from integer to string, there will be no padded zeros. Use int() function to convert the string into the integer.
Charlie Munro says:Yes, zfill(n) is quick and easy. If you want flexibility make sure you know about str.format(). For example: print('<0:03d>'.format(n)) Lot’s of options there for int and float. Used it in a problem on HackerRank yesterday.
Aniruddha Chaudhari says:Yeah, you Right! There are so many options for doing this in Python. The one you have mentioned is even good to go for those having a good understanding of str.format() .
Harry says:I am trying to increase the security of an algorithm by introducing padding using ljust() , the problem is on decryption, I need to get the stream without padding how do I achieve this?