Python programming : List and tuples

List
Introduction

Used for storing different types of data unlike arrays
Example-1 student = [10, "Amar", 'M', 50, 55, 57, 67, 47]
Example-2 e_list = [] #Empty List

Indexing + Slicing can be applied on list
Example-1 print(student[1]) Gives "Amar"
Example-2 print(student[0: 3: 1])
Prints [10, "Amar", 'M']
Example-3 student[::] Print all elements

List
Examples
Example-1 #Create list with integer numbers
num = [10, 20, 30, 40, 50]
print(num)
print("num[0]: %dtnum[2]: %dn" % (num[0], num[2]))
Example-2 #Create list with strings
names = ["Ram", "Amar", "Thomas"]
print(names)
print("names[0]: %stnames[2]: %sn" % (names[0], names[2]))
Example-3 #Create list with different dtypes
x = [10, 20, 1.5, 6.7, "Ram", 'M']
print(x)
print("x[0]: %dtx[2]: %ftx[4]: %stx[5]: %cn" %(x[0], x[2], x[4], x[5]))

List
Creating list using range()
Example #Create list
num = list(range(4, 9, 2))
print(num)

List
Updating list
1 Creation lst = list(range(1, 5))
print(lst)
[1, 2, 3, 4]
2 append lst.append(9)
print(lst)
[1, 2, 3, 4, 9]
3 Update-1 lst[1] = 8
print(lst)
[1, 8, 3, 4, 9]
4 Update-2 lst[1: 3] = 10, 11
print(lst)
[1, 10, 11, 4, 9]
5 delete del lst[1]
print(lst)
[1, 11, 4, 9]
6 remove lst.remove(11)
print(lst)
[1, 4, 9]
7 reverse lst.reverse()
print(lst)
[9, 4, 1]

List
Concatenation of Two List
'+' operator is used to join two list
Example x = [10, 20, 30]
y = [5, 6, 7]
print(x + y)

List
Repetition of List
'*' is used to repeat the list 'n' times
Example x = [10, 20, 30]
print(x * 2)

List
Membership of List
'in' and 'not in' operators are used to check, whether an element belongs to the list
or not
Example x = [1, 2, 3, 4, 5]
a = 3
print(a in x)
Returns True, if the item is found
in the list
Example x = [1, 2, 3, 4, 5]
a = 7
print(a not in x)
Returns True, if the item is not
found in the list

List
Aliasing And Cloning Lists
Aliasing: Giving new name for the existing list
Example x = [10, 20, 30, 40]
y = x
Note: No separate memory will be allocated for y
Cloning / Copy: Making a copy
Example x = [10, 20, 30, 40]
y = x[:] <=> y = x.copy()
x[1] = 99
print(x)
print(y)
Note: Changes made in one list will not reflect other

List
Exercise
1. To find the maximum & minimum item in a list of items
2. Implement Bubble sort
3. To know how many times an element occurred in the list
4. To create employee list and search for the particular employee

List
To find the common items
#To find the common item in two lists
l1 = ["Thomas", "Richard", "Purdie", "Chris"]
l2 = ["Ram", "Amar", "Anthony", "Richard"]
#Covert them into sets
s1 = set(l1)
s2 = set(l2)
#Filter intersection of two sets
s3 = s1.intersection(s2)
#Convert back into the list
common = list(s3)
print(common)

List
Nested List
#To create a list with another list as element
list = [10, 20, 30, [80, 90]]
print(list)

List
List Comprehensions
Example-1: Create a list with squares of integers from 1 to 10
#Version-1
squares = []
for x in range(1, 11):
squares.append(x ** 2)
print(squares)
#Version-2
squares = []
squares = [x ** 2 for x in range(1, 11)]
print(squares)

List comprehensions represent creation of new lists from an iterable object(list, set,

tuple, dictionary or range) that satisfies a given condition

List
List Comprehensions
Example-2: Get squares of integers from 1 to 10 and take only the even numbers from the
result
even_squares = [x ** 2 for x in range(1, 11) if x % 2 == 0]
print(even_squares)



List
List Comprehensions
Example-3: #Adding the elements of two list one by one
#Example-1
x = [10, 20, 30]
y = [1, 2, 3, 4]
lst = []
#Version-1
for i in x:
for j in y:
lst.append(i + j)
#Version-2
lst = [i + j for i in x for j in y]
#Example-2
lst = [i + j for i in "ABC" for j in "DE"]
print(lst)



Tuple
Introduction

A tuple is similar to list but it is immutable

Tuple
Creating Tuples
To create empty tuple
tup1 = ()
Tuple with one item
tup1 = (10, )
Tuple with different dtypes
tup3 = (10, 20, 1.1, 2.3, "Ram", 'M')
Tuple with no braces
t4 = 10, 20, 30, 40
Create tuple from the list
list = [10, 1.2, "Ram", 'M']
t5 = tuple(list)
Create tuple from range
t6 = tuple(range(4, 10, 2))

Tuple
Accessing Tuples

Accessing items in the tuple can be done by indexing or slicing method, similar to
that of list

Tuple
Basic Operations On Tuples
s = (10, "Ram", 10, 20, 30, 40, 50)
To find the length of the tuple
print(len(s))
Repetition operator
fee = (25.000, ) * 4
print(fee)
Concatenate the tuples using *
ns = s + fee
print(ns)
Membership
name = "Ram"
print(name in s)
Repetition
t1 = (1, 2, 3)
t2 = t1 * 3
print(t2)

Tuple
Functions To Process Tuples
len() len(tpl) Returns the number of elements in the tuple
min() min(tpl) Returns the smallest element in the tuple
max() max() Returns the biggest element in the tuple
count() tpl.count(x) Returns how many times the element ‘x’ is found in the tuple
index() tpl.index(x) Returns the first occurrence of the element ‘x’ in tpl.
Raises ValueError if ‘x’ is not found in the tuple
sorted() sorted(tpl) Sorts the elements of the tuple into ascending order.
sorted(tpl, reverse=True) will sort in reverse order

Tuple
Exercise
1. To accept elements in the form of a a tuple and display thier sum and average
2. To find the first occurrence of an element in a tuple
3. To sort a tuple with nested tuples
4. To insert a new item into a tuple at a specified location
5. To modify or replace an existing item of a tuple with new item
6. To delete an element from a particular position in the tuple

Python programming : List and tuples

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