String formatting

str.format()

String formatting uses a string's format method to substitute a number of arguments in the string. Each argument of the format function is placed in the string at the corresponding position, which is determined using the curly braces { }.

# String formatting
nums=[1,2,3]
msg="Numbers {0} {1} {2} ".format(nums[1],nums[0],nums[2])
print(msg)

Numbers 2 1 3 

String formatting can also be done with named arguments.

a="{x} , {y}".format(y=12,x=4)
print(a)

4 , 12

x=42
print('The number is {:b}'.format(x))

The number is 101010

Fstrings (Literal String Interpolation)

After Python 3.6, to create an f-string, prefix the string with the letter “ f ”. The string itself can be formatted in much the same way that you would with str.format(). F-strings provide a concise and convenient way to embed python expressions inside string literals for formatting. Simply it is a shortcut for the format method.

# Prints today's date with help
# of datetime library
import datetime

today = datetime.datetime.today()
print(f"{today:%B %d, %Y}")

July 30, 2021

name = "Eric Idle"
f"{name.lower()} is funny."

eric idle is funny.

x=42
print(f'The number is {x:b}')

The number is 101010

name = 'CarPool'
age = 23
print(f"Hello, My name is {name} and I'm {age} years old.")

Hello, My name is CarPool and I'm 23 years old.

Template string

from string import Template

def main():
    # Usual string formatting with format()
    str1 = "Love {0} and {1}".format("Pollo", "Pitas")
    print(str1)

    # create a template with placeholders
    templ = Template("Love ${title} and ${author}")

    # use the substitute method with keyword arguments
    str2 = templ.substitute(title="Pollo", author="Pitas")
    print(str2)

    # use the substitute method with a dictionary
    data = { 
        "author": "Pitas",
        "title": "Pollo"
    }
    str3 = templ.substitute(data)    
    print(str3)


if __name__ == "__main__":
    main()

Love Pollo and Pitas
Love Pollo and Pitas
Love Pollo and Pitas