Literacy
1. Explain the pros and cons of different ways of checking existence of element in the list.
Terminology
loop – цикл – цикл
element – элемент – элемент
initialize – инициализациялау – инициализировать
conventional – дəстүрлі – обычный
3.4 SWAPELEMENTSINLIST
You will:
Learn to swap elements in a list;
How many ways do you know to swap items from two boxes?
Обмен значениями двух переменных в Python
Обмен значениями двух переменных в Python на самом деле очень простая задача. Python позволяет довольно легко поменять два значения без большого объема кода. Проверьте, насколько легко поменять местами два числа, используя встроенные методы, приведенные ниже:
Example 1
x, y = 21, 64
print(x, y)
x, y = y, x
print(y, x)
Output
21 64 64 21
Python program to swap two elements in a list
Below given a program that swaps the two elements with given positions in the list.
Since the positions of the elements are known, we can simply swap the positions of the elements.
Example 2
List = [23, 65, 19, 90]
pos1, pos2 = 1, 3
print(“List before swapping: “, List)
List[pos1], List[pos2] = List[pos2], List[pos1]
print(“List after swapping 1st and 3rd
elements:”)
print(List)
Intput
List = [23, 65, 19, 90], pos1 = 1, pos2 = 3
Output
List before swapping: [23, 65, 19, 90]
List after swapping 1st and 3rd elements:
[23, 90, 19, 65]
Practice 1
1. Create new blank list
2. Add numbers from 1 to 10 using loop.
3. Swap elements with index 3 and 7.
4. Swap elements with index 3 and 5.
5. Print List before and after swapping.
Practice 2
1. Create new blank list
2. Add ODD numbers from 3 to 20 using loop.
3. Swap elements with index 2 and 6.
4. Print List before and after swapping.
list.pop()
pop() - извлечение элемента из списка, функция без параметра удаляет по умолчанию последний элемент списка.
Example 3
List = [ 1, 2, 3, 4]
print(List.pop())
print(“New List after pop: “, List)
Output
4
New List after pop: [1, 2, 3]
Example 4
List = [1, 2, 3, 4]
print(List.pop(2))
print(“New List after pop: “, List)
Output
3
New List after pop: [1, 2, 4]
Swap items in a list using Inbuilt list.pop() function
Pop the element at pos1 and store it in a variable. Similarly, pop the element at pos2 and store it in another variable. Now insert the two popped element at each other’s original position.
Example 5
List = [23, 65, 19, 90]
pos1, pos2 = 1, 3
print(“List before swapping: “, List)
first_element = List.pop(pos1)
second_element = List.pop(pos2 - 1)
List.insert(pos1, second_element)