Different types of Python String Formatting

String Formatting is the easiest way of combining multiple values to a string. The advantage here is that we can easily combine different datatypes to the string in different formats. Doing the same using the '+' symbol makes it difficult to read and is prone to unexpected errors.

To insert some content to a string, we can use {} as place holders. Within bracket provide name or index. Format type option can be provided as second parameter. Some common formats are decimal(:d), number(:n), percentage(:%). Number of decimal places to display can be indicated after :.

s1 = "String with 2 values: {0} and {1}".format("One", 2)
s2 = "String with 2 values: {first} and {second}".format(first ="One", second =2)
print (s1)
print (s2)
marksPercent = "Marks Percent is {:.1%}"
print(marksPercent.format(0.7522))

We will go through different formatting types in detail below.

We can format a given number to percentage as below. Output value is provided number multiplied by 100. We can manage number of decimal places to display as well.

num = .825
str1 = "Percentage is {:%}"
print(str1.format(num))

str1 = "Percentage to 2 decimal places is {:.2%}"
print(str1.format(num))

str1 = "Percentage to 0 decimal places is {:.0%}"
print(str1.format(num))

Convert numbers in any other format to decimal format.

#Binary to decimal
num = 0b10101
str1 = "Decimal number is {:d}"
print(str1.format(num))

#Octact to decimal
num = 0O10101
str1 = "Decimal number is {:d}"
print(str1.format(num))


#Hexadecimal to decimal
num = 0x10101
str1 = "Decimal number is {:d}"
print(str1.format(num))

Convert numbers in any format to floating point numbers. Number of digits after decimal point can also be mentioned.

num = 0b10101
str1 = "Fixed point number is {:f}"
print(str1.format(num))

num = 20
str1 = "Fixed point number by 2 decimals is {:.2f}"
print(str1.format(num))
str1 = "Fixed point number by 0 decimals is {:.0f}"
print(str1.format(num))

Convert numbers in any format to binary number.

#Decimal to binary
num = 50
str1 = "Binary number is {:b}"
print(str1.format(num))

#Octact to binary
num = 0O10101
str1 = "Binary number is {:b}"
print(str1.format(num))


#Hexadecimal to binary
num = 0x10101
str1 = "Binary number is {:b}"
print(str1.format(num))

Convert numbers in any format to scientific format. E to display characters in upper case and e for lower case.

#Decimal to scientific
num = 50
str1 = "Scientific number is {:e}"
print(str1.format(num))

#Octact to scientific
num = 0O10101
str1 = "Scientific number is {:E}"
print(str1.format(num))

#Hexadecimal to scientific
num = 0x10101
str1 = "Scientific number is {:e}"
print(str1.format(num))

Convert numbers to octal format.

#Decimal to octal
num = 50
str1 = "Octal number is {:o}"
print(str1.format(num))

#Hexadecimal to octal
num = 0x10101
str1 = "Octal number is {:o}"
print(str1.format(num))

Used to provide space before, after or around the inserted value.
Three options there.

:<20Value placed and after that 20 spaces provided.
:>2020 spaces provided and then value placed.
:^2010 spaces provided on the left and right.

#Left align
num = 50
str1 = "Left aligned number {:<20} inserted"
print(str1.format(num))

#Right align
num = 50
str1 = "Right aligned number {:>20} inserted"
print(str1.format(num))

#Center align
num = 50
str1 = "Center aligned number {:^20} inserted"
print(str1.format(num))

Provide separators , or _ for bigger numbers.

#Comma separator
num = 500000000
str1 = "Comma separated number {:,}"
print(str1.format(num))

#Underscore separator
str1 = "Underscore separated number {:_}"
print(str1.format(num))

Used to indicate -ve or +ve numbers.

num1 = +50
num2 = -100

str1 = "Signed numbers {:=10} and {:=20} with space added"
print(str1.format(num1, num2))

str1 = "Signed numbers {:+} and {:+} added"
print(str1.format(num1, num2))

str1 = "Signed numbers {:-} and {:-} added"
print(str1.format(num1, num2))

To apply multiple formats on the same item, we have to do it separate as below. Here we are trying to make a number fixed point and, provide comma separators also.

num = 1000000.44444
str11 = '{:.2f}'.format(num)
print(str11)
str1 = "Multiple formats applied on number {:,}"
print(str1.format(float(str11)))

String formatting does not have an option to format dates directly. We will have to convert datetime object to string as below and then combine.

Refer Convert Datetime to String - All Formats for converting datetime object to string in different formats.

from datetime import datetime
datetoconvert = datetime(2022, 1, 15, 20, 35, 45, 123456)
stringdate = datetoconvert.strftime('%d-%b-%y')
str1 = "Date is {}"
print(str1.format(stringdate))