Python3 fstrings

vars = 'abc'

print(f 'Variable  is : {vars}')

This is much better than 'Variable is : {}'.format(vars)

Python 2 Vs 3

Python 2	Python 3
input() may store as int, string raw_input() stores str always	input() function was fixed in Python 3 so that it always stores the user inputs as str
print "Hi" print("Hi")	print("Hi")
3/2 ==> floor(1.5) => 1 (defaults to floor), return int	3/2 ==> 1.5
Strings default stores as Ascii	Strings default stores as unicode Unicode is a superset of ASCII and hence, can encode more characters including foreign ones.
sorted(employees.items(), key=lambda(x,y): y['age'])	sorted(employees.items(), key=lambda x: x[1]['age'])
	AsyncIO
	Fstrings
	It is recommended to use __future__ imports it if you are planning Python 3.x support for your code
xrange() - Lazy evaluation	range() - Lazy evaluation
except NameError, err:	except NameError as err:
my_generator = (letter for letter in 'abcdefg') next(my_generator) my_generator.next()	my_generator = (letter for letter in 'abcdefg') next(my_generator)
print 'Python', python_version() i = 1 print 'before: i =', i print 'comprehension: ', [i for i in range(5)] print 'after: i =', i Python 2.7.6 before: i = 1 comprehension: [0, 1, 2, 3, 4] after: i = 4	Python 3.x for-loop variables don’t leak into the global namespace anymore! print ('Python', python_version()) i = 1 print 'before: i =', i print 'comprehension: ', [i for i in range(5)] print 'after: i =', i Python 3.4.1 before: i = 1 comprehension: [0, 1, 2, 3, 4] after: i = 1
print range(3) print type(range(3)) [0, 1, 2] <type 'list'>	print range(3) print type(range(3)) print(list(range(3))) range(0, 3) <class 'range'> [0, 1, 2]
round(15.5) # 16.0 round(16.5) # 17.0	Bankers rounding round(15.5) # 16 round(16.5) # 16

Python fstrings

elem = 10

elem_index = 5

def to_lowercase(st):

return st.lower()

#Formatted string literals (f-strings)

#The idea behind f-strings is to make string interpolation simpler.

#f-strings are expressions evaluated at runtime rather than constant values

print(f'Index of element {elem} is {elem_index}')

#call functions from f-strings

print(f'String to lowercase: {to_lowercase("TEST_STRING")}')

print(f'String to lowercase: {"TEST_STRING".lower()}')

#Format - used in previous versions of python

print('Index of element {} is {}'.format(elem, elem_index))

elapsed = 23.5678

print(f"{__file__} executed in {elapsed:0.2f} seconds.")

Output:

Index of element 10 is 5 String to lowercase: test_string String to lowercase: test_string Index of element 10 is 5
main.py executed in 23.57 seconds.