Quick python revision notes
# formating
name = 'bhagvant'
f = f"this is {name}"
print(f)
# Notice we are not adding f
name = 'bhagvant'
greeting = 'hello {}'
k = greeting.format(name)
################ LIST ###########################
l = ["Bob", "Rolf", "Anne"]
l[0] = "Smith"
l.append("Jen")
# extend allows to add set or tuple to list, l+s will not work , works only for list
s = {"Bob", "Rolf", "Anne"}
l.extend(s)
print(l)
# we can even insert a set to list
l[0] = s
#gets the length of list
len(l)
# Get number of times element appears in list
print(l.count("Bob"))
# to remove element from given inde type POP
l.pop(2)
l.pop() # removes last element
# reverse a list
l.reverse()
# sorts a list
prime_numbers = [11, 3, 7, 5, 2]
prime_numbers.sort()
############ Tuple ##############################
# you can concat 2 tuples but cant , change element of tuple
tuple1 = (0, 1, 2, 3)
tuple2 = ('python', 'geek')
# Concatenating above two
print(tuple1 + tuple2)
################# SET ##########################
# sets are unordered, Cannot contain duplicates and efficient for searching elements
friends = {"Bob", "Rolf", "Anne"}
abroad = {"Bob", "Anne"}
# to Create a set you cant use {} , this will create empty dictionary
a = set()
s.add("Jen")
# set cant have same element twice , its distinct
s.add("Bob")
print(friends.difference(abroad))
# returns empty set
print(abroad.difference(friends))
print(friends.intersection(abroad))
friends = {"Bob", "Rolf", "Anne"}
abroad = {"Bob", "Anne"}
# superset
if friends > abroad :
print('superset')
# subset
if abroad < friends:
print('subset')
# easy to check key in , fastest data structure due to hash table
for name in friends:
if name in abroad:
print(f' {name} gone abroad')
############# Is operator #######################
if 2 variables point to same object
x = 5
y = 5
print(x is y)
############ If condition #####################
dayofweek = 'Monday'
if dayofweek == 'Monday':
print(1)
######### in keyword #################
# The `in` keyword works in most sequences like lists, tuples, and sets.
friends = ["Rolf", "Bob", "Jen"]
print("Jen" in friends)
# --
movies_watched = {"The Matrix", "Green Book", "Her"}
user_movie = input("Enter something you've watched recently: ")
print(user_movie in movies_watched)
############ LOOPS #######################
while n < 5:
print(n)
n+=1
while True:
break
for i in range(10):
print(f'for {i}')
#How to have 2 loops and loop through
for i in range(_size):
k = i + 1
for j in range(k, _size):
# remember when range start and end are equal it will not print
for i in range(1,1):
print('wont print')
# incrementing range by 2 every time
for i in range(0,6,2):
print(i)
########### List comprehension ###################
print([i for i in range(10) if i in [2,4,6]])
######## Dicationaries ##################
friend_ages = {"Rolf": 24, "Adam": 30, "Anne": 27}
print(friend_ages.keys())
print(friend_ages.values())
print(friend_ages['bhagvant'])
# adding to dictionary
friend_ages['bhagvant'] = 54
# Simple
student_attendance = {"Rolf": 96, "Bob": 80, "Anne": 100}
for student in student_attendance:
print(f"{student}: {student_attendance[student]}")
# better
for i,k in friend_ages.items():
print(i,k)
############## Functions #####################
def abc(a=1,b=2):
print('this is function',a,b)
abc(1,3)
def abc(a=1,b=2):
print('this is function',a,b)
c = a+b
return c
total = abc(1,3)
########## Lambda ############################
#map allows to add lambda to sequence
l = [1,2,3,4,5]
sum1 = lambda x:x+1
map_object = map(sum1,l)
print(list(map_object))
# * packs arguments into sinle list
a,*b = 1,2,3,4
print('first',a,b)
# unpacks it into tuple
def abc(k,*a):
print(a)
print(k)
abc(1,2,3,4)
# it packs the values into dictionary
def abc(**kwargs):
print(kwargs)
abc(a='kk',b='jj')
anotherfunctionwithKeyValue(**kwargs)
def abc(**kwargs):
print(kwargs)
# allows to pass it
anotherfunctionwithKeyValue(**kwargs)
abc(a='kk',b='jj')
########## Object oriented programming ###################
class abc:
# notice init has to have self as argument
def __init__(self,a=0,b=0):
self.c = a+b
# all class variables need self
# self has to be passed as argument
def multi(self):
print(self.c)
# used to print info about class , shoudl have a return
def __str__(self):
return f"value of a is {self.c}"
k = abc(1,1)
k.multi()
# str gets called when you print class ref
print(k)
