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Standard Normal Distribution with examples using Python

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Easy Guide to using f-strings in Python with examples

Easy Guide to using f-strings in Python with examples

f-strings were introduced in Python 3.6. String formatting has been made simpler with f-strings. f-strings are of the form f" " or f' '. Let's look at some examples to understand this better.

How to print a variable using f-strings?

  
name = "James Bond"
drink = "martini"
serving_type = "shaken and not stirred"
f"My name is {name} and I like my {drink} {serving_type}"
--->My name is James Bond and I like my martini shaken and not stirred

f-strings use a { } to evaluate any expression and format it as a string. The above example evaluates each of the variables within curly braces and formats it as string.

How to use mathematical expressions with f-strings

  
f"2x2 = {2*2}"
--->2x2 = 4
f"Square of 8 is {8**2}
---> Square of 8 is 64

Practically anything can be put inside the { } as long as the expresson evaluates to something concrete. 2*2 and 8**2 are evaluated and presented in string format. Is this all which can be done? What else can be done?

How to make a function call within f-strings?


def square_of_no(x):
  return x**2
f"Square of 8 is {square_of_no(8)}"
--->Square of 8 is 64

How to make use of lambda function within f-strings?


f"Square of 8 is {(lambda x:x**2)(8)}"
--->Square of 8 is 64
f"Sum of a^2 and b^2 is { (lambda x,y: x**2+y**2)(4,6) }"
---> Sum of a^2 and b^2 is 52

How to use dictionaries within f-strings?


dict_age = {'Rohit':38, 'Harry':43, 'Samarth': 7, Jessy': 56}
f"Age of Rohit is {dict_age.get('Rohit')} years and Age of Samarth is {dict_age.get('Samarth')} years"
--->Age of Rohit is 38 years and Age of Samarth is 7 years

We will slightly modify the above code now. Observe that we are now referencing the keys of dictionary with double quotes " " instead of single quotes ' '. 


dict_age = {'Rohit':38, 'Harry':43, 'Samarth': 7, 'Jessy': 56}
f"Age of Rohit is {dict_age.get("Rohit")} years and Age of Samarth is {dict_age.get("Samarth")} years"
--->f"Age of Rohit is {dict_age.get("Rohit")} years and Age of Samarth is   {dict_age.get("Samarth")} years"
SyntaxError: invalid syntax

We used double quotes to begin the f-string syntax. Hence we cannot reference keys of the dictionary using double quotes. It can be referenced using single quotes only. On the contrary, if we begin the f-string using single quotes, we can only use double quotes to reference the keys of the dictionary. Let's see this in action. 


f'Age of Rohit is {dict_age.get("Rohit")} years and Age of Samarth is {dict_age.get("Samarth")}'
---> Age of Rohit is 38 years and Age of Samarth is 7
f"Age of Rohit is {dict_age.get('Rohit')} years and Age of Samarth is {dict_age.get('Samarth')} years"
--->Age of Rohit is 38 years and Age of Samarth is 7 years

How to use Multiline f-strings in Python? 

  
day1 = "Sunday"
day2 = "Monday"
info = f"Today is {day1}."
   f"Tomorrow is {day2}."
   f"I hope {day1} never ends."
print(info)

Using an Escape character \ is equally valid after each line.

  
day1 = "Sunday"
day2 = "Monday"
info = f"Today is {day1}."\
      f"Tomorrow is {day2}."\
      f"I hope {day1} never ends.  "
print(info)
---> Today is Sunday.Tomorrow is Monday.I hope Sunday never ends.

It is important to put f" " on each line. Otherwise results may not be as expected. Let's see what happens if we do that. 

  
day1 = "Sunday"
day2 = "Monday"
info = f"Today is {day1}."\
   "Tomorrow is {day2}."\
   "I hope {day1} never ends."
print(info)
--->Today is Sunday.Tomorrow is {day2}.I hope {day1} never ends.

If we want each sentence on a new line, we use \n character

    
day1 = "Sunday"
day2 = "Monday"
info = f"Today is {day1}.\n"\
      f"Tomorrow is {day2}.\n"\
      f"I hope {day1} never ends.\n "
print(info)
--->Today is Sunday.
    Tomorrow is Monday.
    I hope Sunday never ends.

If you want to know about formatting numerical and float values using f-strings, you can have a look at this post.

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