Python format padding zero

Python Pad String With Zeros

How to pad string with zeros in Python? Adding some characters/values to the string is known as Padding. In Python, zfill() and rjust() methods are used to pad zeros at the beginning of the string and ljust() is used to pad zeros at the end of the string. With the ljust() and rjust() you can fill in any characters but in this article, I will use them to fill in zeros.

Alternatively, by using f-strings, we can pad zeros to the string in two ways. Using ‘>’, we can pad zeros at left, and using ‘

1. Quick Examples of padding zeros to string

Following are quick examples of how to pad or fill zeros to the string to get a specific length of a string.

") # Pad right using f-strings print(f"30>'".format(string1)) # Pad right using format() print(''.format(string1)) 

2. Pad Zeros to String using rjust()

The rjust() method is Python’s str class that is used to pad zeros on the left of the python string (string is aligned to the right). This method takes two arguments: the minimum width of the string as value, and an optional padding character (which is a space by default).

This method returns a new string with the specified width after padding the fill character to the original string. For example, If your string length is 6, and the value specified inside rfill() is 10, then 4 zeros are padded to the left of the string, so the final length of the string is 10.

2.1 rjust() Syntax

2.2 rjust() Parameters

1. value is the first parameter that specify the total length of the string after padding zeros.
2. Second parameter takes the element that has to be padded to the string. In our case, it is ‘0’.

2.3 Pad Zeros to the Left of the String

Let’s create a string and pad the zeros at the start (left of the string).

3. Pad Zeros to String using ljust()

The ljust() method is also Python’s str class that is used to pad zeros on the right of the python string (string is aligned to the left). This method also takes two arguments: the minimum width of the string as value, and an optional padding character (which is a space by default).

If your string length is 7, and the value specified inside rfill() is 10, then 3 zeros are padded to the right of the string, so the final length of the string is 10.

3.1 ljust() Syntax

Following is the syntax of the ljust()

3.2 ljust() Parameters

1. value is the first parameter that specifies the total length of the string after padding zeros.
2. Second parameter takes the element that has to be padded to the string. In our case it is ‘0’.

3.3 Example

By using ljust() method, let’s pad zeros at the end of the string.

4. Pad Zeros to String using zfill()

The zfill() is used to fill the string with zeros at the start of the string (left of the string). It takes the value as a parameter that specifies the total length of the string along with zeros. By default, zfill() treats the string as a numeric value and removes any leading plus or minus sign. If you want to preserve the sign, you can pass the sign parameter as ‘+’ or ‘-‘

If you have a string length of 6 and specify 10 as the length, zfill() returns a string with the length 10 that includes 4 zeroes on the left.

4.1 zfill() Syntax

Let’s look at the syntax of zfill()

4.2 Example

Here, let’s use the zfill() to fill the zeros on the left of the string.

5. Pad Zeros to String using f-strings

1. If we specify element > value, zeros are padded at the start of the string (left padding).
2. If we specify element < value, zeros are padded at the end of the string (right padding).

The value specified will be equal to the length of the string after padding.

5.1 f-strings Syntax

Let’s look at the syntax of f-strings with left and right paddings.

 value>" # Syntax of Right padding f"" 

5.2 Example

Create a string with 6 characters and pad zeros by specifying different values at Left and Right using f-strings.

10>") # Pad right print(f"") # Output: # String: PYTHON # 0000PYTHON # PYTHON0000 

• First example – 4 zeros are Left padded by specifying the value as 10.
• Second example – 4 zeros are Right padded by specifying the value as 10.
• In both outputs, the length of the final string is 10, as the value is 10.

6. Pad Zeros to String using format()

Finally, format() in python is used to display the strings in the desired formats similar to f-strings. It can be used to pad zeros at Left and Right with > and < operators. But we need to specify this inside <>.

The value specified will be equal to the length of the string after padding.

6.1 format() Syntax

Let’s look at the syntax of format() with Left and Right Paddings.

 value>'.format(string1) # Syntax of Right padding ''.format(string1) 

6.2 Example

Let’s use the ‘<>’ .format() to pad or fill zeros on the left and right of the string in python.

10>'.format(string1)) # Pad right print(''.format(string1)) # Output: # String: PYTHON # 0000PYTHON # PYTHON0000 

7. Conclusion

In this article, you have learned zfill() and rjust() is used to fill or pad the zeros on the left of the string, and ljust() is used to fill on the right of the string in Python. Alternatively, you can also use f-string and format() to fill the zeros on the string to get the desired width of the stirng.

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How to pad zeros to a string in Python?

In this article, we will learn to pad zeros to a given string using the Python programming language. Padding zeros can be useful when you have to make a string of desired length. You can do this by adding zeros to the beginning or to the end of the string. In these methods below, in place of zero you can also add any other numbers, string or special characters according to your needs.

Table Of Contents

Make sure to read these articles thoroughly and always try to run these codes in your machine. Here i have used Python 3.10.1 for writing example codes. To check your version write python –version in your terminal.

Pad zeros to a string using format() and F-string

Let’s discuss what are format() and F-string methods and how to use them to pad zeros in a string.

format() method:

format() is the built-in string class which provides formatting options of the strings in python.

Frequently Asked:

It recives only one parameter which is the str/value which needs to formatted.

We can use this method to pad zeros in a string. See the example code below :

str_var = "Padding zeros using Format Method <>" # Pad zeros to the right of string str_var = str_var.format('0000') print(str_var)

Padding zeros using Format Method 0000

You can see in code above, through format() method we can add zeros at the place of curly braces . You can always position the curly braces according to your requirement.

F-String :

Introduced in Python 3.6, the F-String are also a very fast and less error prone method of formatting strings. Also known as Literal String Interpolation. Lets see an Example code :

zeros = '0000' str_value = f"Padding zeros using F-String " print(str_value)

Padding zeros using F-String 0000

In code above you can see that by using F-String, we can also pad zeros. Both the F-string and format() method are kind of simillar. Because they both have curly braces which is known as replacement fields.

Pad zeros to a string using zfill() method :

Next we will be using zfill() method to pad zeros to a string. This method takes a number as an argument and adds zeros to the left of the string until the length of the number reaches to the parameter provided. Lets See an Example :

str_var = 'Padding zeros using zfill method.' # this will print the length of str_var print(len(str_var)) str_var = str_var.zfill(40) print(str_var) # this will print the length of str_var # after padding zeros which should be equal to 40. print(len(str_var))

34 000000Padding zeros using zfill method. 40

As you can see in the code and output above length of str_var before padding zeros was 34. Parameter 40 has been provided , which means length of the str_var should be 40. So zfill() method padded 6 zeros on the left of str_var.

Pad zeros to a string using ljust(), rjust() and str.center()

Now we will be using some methods of string class to pad zeros to a string. As name suggests of the methods,

• ljust() method is used align string to left and pad zereos to right.
• rjust() method is used to align string to right and pad zeros to left.
• str.center() can be used to align string to center and pad zeros to both left and right of the string.

Above all methods take two arguments :

• First is width or desired length of the string.
• Second is character with which you want the empty space to be filled.

ljust() method :

str_var = "Height of Mount Everest is 8,848.86 m." # pad zeros on the right to make string length 60 str_var = str_var.ljust(60,'0') print(str_var)

Height of Mount Everest is 8,848.86 m.0000000000000000000000

rjust() method :

str_var = "Height of Mount Everest is 8,848.86 m." # pad zeros on the left to make string length 60 str_var = str_var.rjust(60,'0') print(str_var)

0000000000000000000000Height of Mount Everest is 8,848.86 m.

str.center() method :

str_var = "Height of Mount Everest is 8,848.86 m." # pad zeros on both right and left to make string length 60 str_var = str_var.center(60,'0') print(str_var)

00000000000Height of Mount Everest is 8,848.86 m.00000000000

You can see in methods above how we can pad zeros and also align zeros according to our needs using ljust(), rjust() and str.center() methods.

Summary

So , we have seen three different methods with which we can pad zeros to a given string in Python Programming language. Using the third method gives a benifit over other two. With ljust() ,rjust() and str.center() we can align our zeros according to our needs. If we need zeros to be padded in between string so we can use the first method, which is format() or F-string method. With the help of curly braces we can place zeros or any other data type at our desired position.

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