Small Programs using Python

 1. How to find the minimum value in a list?

Primitive: 

lst = [3, 6, 7, 2, 1, 5]

print(min(lst))

Object:

lst = [Car('Nano', 150), Car('Ferrari', 500), Car('Maruti', 250)]

new_lst = min(lst, key=lambda car: car.max_speed)

2. How to get a list sorted?

Primitive: 

lst = [3, 6, 7, 2, 1, 5]

sort(lst)

Object:

lst = [Car('Nano', 150), Car('Ferrari', 550), Car('Maruti', 250)]

new_lst = sorted(lst, key=lambda car: car.max_speed)

Reverse Order:

new_lst = sorted(lst, key=lambda car: car.max_speed, reverse=True)

3. How to reverse a String or a List?

List of Primitives: 

lst.reverse()

list(reversed(lst))

lst[::-1] 

String:

list(string).reverse()

string = "".join(reversed(string))

str[::-1]

List of Objects:

sort in reverse order.

4. How to search an element?

List of Primitives: 

lst = [3, 6, 7, 2, 1, 5]

print(6 in lst)

print(lst.index(6) > -1)

String: 

str = 'Eleven boys have a good football court.'

result = str.find('ball')

List of Objects:

lst = [Car('Nano', 150), Car('Ferrari', 500), Car('Maruti', 250)]

print(any(filter(lambda car: car.max_speed > 400, lst)))

# filter returns iterator, list(filter()) returns list

print(any(car for car in lst if car.max_speed > 400))

5. How to count the occurrences?

List of Primitives: 

lst = [3, 6, 7, 2, 1, 5]

print(lst.count(2))

String: 

str = 'Eleven boys have a good football court.'

print(str.count('o'))

List of Objects:

lst = [Car('Nano', 150), Car('Ferrari', 500), Car('Maruti', 250)]

print(len(filter(lambda car: car.max_speed > 400, lst)) )    

print(len([car for car in lst if car.max_speed > 400])) # square bracket same as list( ).

6. How to replace an element?

List of Primitives: 

lst = [3, 6, 7, 2, 1, 5]

lst[2] = 17

list(map(lambda x: x+10, lst))           

String: 

str = 'Eleven boys have a good football court.'

str = str.replace('boys', 'girls')

List of Objects:

lst = [Car('Nano', 150), Car('Ferrari', 500), Car('Maruti', 250)]

#   list of map of lamba cannot be used for changing object's state, it can only replace an object.

for car in lst:

    if car.max_speed > 450:

        car.max_speed = 450