Python. Lists. Functions and methods

11.2.3.3 apply functions and methods of processing lists

Python. Lists. Functions and methods

A list is an ordered composite data type, a mutable collection of items of different types.

Functions/methods of lists.

Notes:

lisls: lst, lst1, lst2, nums
element of list: x
index: i
interger: n

Function/Method Example Describtion

x in lst

lst = [2, 3, 4]
print(3 in lst) # True
print(5 in lst) # False

Checking that x is contained in lst
x not in lst

print(3 not in [2, 3, 4]) # False
print(5 not in [2, 3, 4]) # True

Checking that x is not contained in lst
lst1 + lst2
lst1 += lst2

lst1 = [1, 2]
lst2 = [3, 4]
print(lst1 + lst2) # [1, 2, 3, 4]

Concatenation of lists. A new list that contains first the elements lst1 and then all the elements lst2

lst * n
lst *= n

lst = [2, 3]
print(lst * 3) # [2, 3, 2, 3, 2, 3]

List lst repeated n times
lst[i]

lst = ['A', 'B', 'C', 'D']
print(lst[1]) # B
print(lst[-2]) # C

i-th element of the list,
negative i - for counting from the end
lst[start:stop:step]

lst = ['A', 'B', 'C', 'D']
print(lst[1:3]) # ['B', 'C']
print(lst[::2]) # ['A', 'C']

Slice of the list
len(lst) lst = ['A', 'B', 'C', 'D']
print(len(lst)) # 4
List length
max(lst) nums = [9, 7, 4, 6]
print(max(nums)) # 9
Maximum list item
min(lst) nums = [9, 7, 4, 6]
print(min(nums))  # 4
Minimum list item
sum(lst) nums = [9, 7, 4, 6]
print(sum(nums))  # 26
Sum of list items
lst.index(x) nums = [9, 7, 4, 6]
print(nums.index(4))  # 2
Index of the first occurrence of x in lst
(give an error if x is not in lst)
lst.count(x) nums = [7, 7, 4, 6, 7]
print(nums.count(7))  # 3
The number of occurrences of x in lst

lst.append(x)

 

 

lst.insert(i, x)

nums = [2, 7, 4]
nums.append(6)
print(nums)  # [2, 7, 4, 6]

nums = [2, 7, 4]
nums.insert(1, 6)
print(nums)  # [2, 6, 7, 4]
nums.insert(10, 3)
print(nums) # [2, 6, 7, 4, 3]

Add x to the end of lst

 

Insert x to the lst[i] position. Elements to the right of insertion change index to i + 1

lst1.extend(lst2) lst1 = [2, 7]
lst2 = [4, 6]
lst1.extend(lst2)
print(lst1) # [2, 7, 4, 6]
Add elements of collection lst2 to the end of lst1
del lst[i] nums = [9, 7, 4, 6]
del nums[1]
print(nums) # [9, 4, 6]
Remove the i-th element of the list
del lst[start:stop:step] nums = [9, 7, 4, 6]
del nums[:2]
print(nums) # [4, 6]
Remove all elements from lst that are in the slice
lst.clear() nums = [9, 7, 4, 6]
nums.clear()
print(nums) # []

Remove all elements from lst
(same as del lst[:])

lst.copy() nums = [9, 7, 4, 6]
lst = nums.copy()
print(lst) # [9, 7, 4, 6]
Copy of list
(same as lst[:])
lst.remove(x) nums = [9, 7, 4, 6]
nums.remove(7)
print(nums) # [9, 4, 6]
Delete the first occurrence of x in lst,
in case x not in lst - an error
lst.pop(i)

nums = [9, 7, 4, 6]
nums.pop(2)
print(nums) # [9, 7, 6]
nums.pop()
print(nums) # [9, 7]

Get the ith element of the list and remove it from the list at the same time.
With no arguments, removes the last element:
a.pop () == a.pop (-1)
lst.reverse() nums = [9, 7, 4, 6]
nums.reverse()
print(nums) # [6, 4, 7, 9]
Reverse the order of elements in a (reverse the list)
lst.sort() nums = [9, 7, 4, 6]
nums.sort()
print(nums) # [4, 6, 7, 9]
Sort the list in ascending order
lst.sort(reverse=True) nums = [9, 7, 4, 6]
nums.sort(reverse=True)
print(nums) # [9, 7, 6, 4]
Sort the list in descending order
bool(lst) lst = ['apple']
print(bool(lst)) # True
lst.pop()
print(bool(lst)) # False
Checking a list for emptiness

 

Questions:

  1. What is the data structure 'list'?
  2. Provide features of the data structure 'list'?
  3. Name three functions of the data structure 'list'.
  4. Name three methods of the data structure 'list'.

Exercises:

Ex.1 Identify result of outputs (Designed by Mr. Halil Mali - CS teacher of NIS Uralsk) 

Ex.2 Identify result of outputs (Designed by Mr. Halil Mali - CS teacher of NIS Uralsk)

Ex.3 Identify result of outputs (Designed by Mr. Halil Mali - CS teacher of NIS Uralsk)

Ex.4 Identify result of outputs (Designed by Mr. Halil Mali - CS teacher of NIS Uralsk)

Tasks:

 

Категория: Programming languages | Добавил: bzfar77 (05.01.2022)
Просмотров: 678 | Теги: Sort, Remove, Count, Python, pop, Copy, Index, append, Extend, Reverse, INSERT, clear, data structure, List, Item | Рейтинг: 5.0/1
Всего комментариев: 0
avatar