FINAL revised LIST in Python.pdf

Mrs. Payal Bhattacharjee, PGT(C.Sc.)
K V No.1 Kanchrapara
KVS-RO(Kolkata)
Know Python Bytes
www.knowpythonbytes.blogspot.com

 Lists Introduction: Definition, Creation of a list, Traversal of a list.
 Operations on a list – concatenation/joining, repetition/replication,
membership, Comparison of Lists;
 Functions/methods–len(), list(),append(), extend(), insert(), count(),
index(), remove(), pop(), reverse(), sort(),min(), max(), sum()
 Lists Slicing;
 Nested lists;
 finding the maximum, minimum, mean of numeric values stored in a list
 linear search on list of numbers
 counting the frequency of elements in a list
CONTENTS
( Learning Outcomes ) 
XI CS 2020-21
XI IP 2020-21
Lists: list operations - creating, initializing, traversing and manipulating
LIST in Python

What is a LIST ?
• A list is a collections of items which are
formed by placing a comma-separated-
list of expressions in square brackets.
• Each item/element has its own index
number.
• Index of first item is 0 and the last item
is n-1. Here n is number of items in a
list.
• Lists are mutable sequences i.e. we can
change elements of a list in place.
• Lists can contain values of mixed data
types.
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list.
Operations on a list -
Functions/methods
 Lists Slicing;
 Nested lists;
finding the maximum,
minimum, mean
 linear search on list
 counting the frequency
CONTENTS

INDEXING in a LIST
0 1 2 3 4 5
-6 -5 -4 -3 -2 -1
B A C K W A R D I N D E X D I R E C T I O N
10 20 30 40 50 60
F O R W A R D I N D E X D I R E C T I O N
NOTE:-
The index (also called subscript) is the numbered
position of a letter in the LIST. In python, indices begin
from
0,1,2,…. upto (length-1) in the forward
direction and
-1,-2,-3,….. (-length) in the backward direction.
where length is the length of the List.
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
Operations on a list
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS

CREATION of LIST
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
List of numbers created without name
List of characters created without name
List of mixed data type created without
name
List of numbers with name L
Empty List created without name
Empty List created with name L
Empty List created with name l using
funcion list()

CONTENTS
Creation of LIST contd..(Long List and Nested List)
Creation of a long listwith name MultiTens
Creation of a Nested List with name L
that is List inside a List
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
 Lists Slicing;
 Nested lists;
minimum, mean

CONTENTS
Creation of LIST from existing sequences
Creating list from string
Creating list by taking input from the keyboard(user)
Creating list from tuple
**Note: All the elements are considered as string
Creating list by taking input from the keyboard [using eval()]
]method]
**Note: eval( ) identifies the type by looking at the given
expression
Lists Intro:
List Definition
Indexing in a List
Creation of a list
from string,tuple,
list(input()),
eval(input())
Traversal of a list
Assign/change values in List
 Lists Slicing;
 Nested lists;
minimum, mean

Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
Assign /change values in List
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
TRAVERSAL of a LIST

CONTENTS
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
Assign /change values in List
 Lists Slicing;
 Nested lists;
minimum, mean
TRAVERSAL of NESTED LIST
Nested List 1 Nested List 2
Enclosing List
Note: Denoting Nested elements
using Index nos.
M[0]  10
M[1]  [15,30]
M[1][0]15
M[1][1]30
M[2] *80,’Mask’,60+
M[2][0]80
M[2][1]‘Mask’
M[2][2]60

CONTENTS
Lists Intro:
List Definition
Indexing in a List
Creation of a list
Traversal of a list
Assign /change
values in List
 Lists Slicing;
 Nested lists;
minimum, mean
Assign/Change values in a LIST
Assigning
/ Changing
values of
elements
of a List
Assigning /
Changing
values of
elements of
a List
Forward Index 0 1 2 3
-4 -3 -2 -1 Backward index

Lists Introduction:
OPERATIONS
ON List
Concatenation/Joining
Repetition/Replication
Membership
Comparison of Lists
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS List CAN be concatenated or
joined with another List
List CANNOT be concatenated with a number
List CANNOT be concatenated with a string
List CANNOT be joined with a complex nos.
List CAN be concatenated or
joined with another List
Concatenation refers
to Joining of two
objects
OPERATIONS on LIST Concatenation

CONTENTS
OPERATIONS
ON List
Repetition/
Replication
Membership
Comparison of Lists
 Lists Slicing;
 Nested lists;
minimum, mean
OPERATIONS on LIST Replication
Replicating the unnamed List two times
Replicating the named List RL four times
Replication refers to Repetition of objects as it
is. Here, in LIST we can see NON-VECTORISED
operation with a list where the entire list as a
whole is replicated.
NOTE: Vectorised operation, refers to the
replication of individual elements of the object.

CONTENTS
OPERATOR DESCRIPTION
in Results to True value if it finds a variable at the LHS of in
operator in the sequence mentioned in the RHS of the in
operator, else it returns False
not in Results to True value if it does not find a variable at the
LHS of in operator in the sequence mentioned in the RHS
of the in operator, else it returns False
Membership operator tests for Membership in a sequence.
Returns Boolean True or False
OPERATIONS
ON List
Repetition/
Replication
Membership
in List
Comparison of Lists
 Lists Slicing;
 Nested lists;
minimum, mean
OPERATIONS on LIST Membership

CONTENTS Comparison of list returns Boolean True or False.
OPERATIONS
ON List
Repetition/
Replication
Membership in List
Comparison
of Lists
 Lists Slicing;
 Nested lists;
minimum, mean
OPERATIONS on Comparison of LIST
Eg. List CANNOT be
compared with a number
Relational operators
==,!=,<,<=,>,>= are used
in comparing two objects.
Here, for example two List
objects are compared.
Relational operators ==,!=
can be used in comparing
two objects eg. List with
number/string/tuple. But,
Relational operators
<,<=,>,>= always returns
ERROR when used in
comparing two objects eg.
List with
number/string/tuple.

Functions / Methods on LIST-len()
TOTAL 5 elements of the List object
len() function counts the no. of elements in the List
Functions/
methods
len(), list(),append(),
extend(), insert(),
count(),index(), remove(),
pop(), reverse(), sort(),
min(), max(), sum(),clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS

Functions/
methods
extend(), insert(),
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
Functions / Methods on LIST-list()
The list() function creates a list object.
A list object is a collection which is ordered and
changeable.
list() function
takes
elements/values
inside the
parantheses i.e. ()
NOTE: Python language is case-sensitive.
Here, Z is the List object , so, z in small letters gives an error.

Functions/
methods
extend(), insert(),
pop(), reverse(),
sort(),min(), max(),
sum(),clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS The append() function takes one single parameter
and adds exactly one element at the end of the List.
It takes exactly one element and returns no value.
Here, append() function takes one single
parameter . In this example, 30.
Functions / Methods on LIST-append()

extend(), insert(),
 Lists Slicing;
 Nested lists;
finding the max,min, mean
The extend() function adds iterable (Eg. Another List/
Tuple/String) at the end of the List.
Here, trying to extend list A , with another
unnamed List containing one element [30].
Functions / Methods on LIST-extend()
CONTENTS
Here, trying to extend list A , with
another unnamed List containing
three elements [4,50,77].
Here, trying to extend list A , with
another named List B containing
three elements
*‘know’,’python’,’bytes’+
Here, trying to extend list A , with a number 10. Hence error !!!
NOTE: A no. inside parentheses () is not a tuple,
until it ends with a comma ,
Here, trying to extend list A , with an unnamed tuple with two values
Here, trying to extend list A , with a string.
Every character is considered as an element of the list.

len(), list(),append(), extend(),
insert(), count(),index(),
remove(), pop(), reverse(),
sum(),clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
Functions / Methods on LIST- insert()
insert( ) method,
inserts an item / element at a given position.
It takes two arguments and returns no value.
ListObject.insert(<position>,<item>)
Position denotes the index no.
Item denotes the item/element/value to be inserted.
Forward Index 0 1 2
-3 -2 -1 Backward index
NOTE: Whenever the element is inserted,
whether forward or backward index… it is
always inserted at the left hand side of the
current index item’s position.
Prepended inserted at the beginning i.e.
index 0
Appended  inserted at the last

Functions/
methods
extend(), insert(),
count()
,index(),remove(), pop(),
reverse(), sort(),min(),
max(), sum(), clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
Functions / Methods on LIST- count()
count( ) method,
returns the count of the item (no. of times the
item /element/value appears) that is passed as
argument. If the given item is not in the list, it
will return 0

Functions/
methods
insert(),count(), index(),
sort(),min(), max(), sum() ,
clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
Functions / Methods on LIST- index()
index( ) method,
returns the index of the first matched item.
Forward
Index 0 1 2 3 4 5

Functions/
methods
insert(),count(),index(),
remove(), pop(),
reverse(), sort(),min(), max(),
sum() , clear()
 Lists Slicing;
 Nested lists;
minimum, mean
CONTENTS
Functions / Methods on LIST- remove()
remove( ) method,
removes the first occurrence of given item from the
list (from left-to-right)
remove( ) will report an error if there is no such value.

CONTENTS
Functions / Methods on LIST- pop()
Functions/
methods
extend(),
remove(), pop(),
max(), sum() , clear()
 Lists Slicing;
 Nested lists;
minimum, mean
pop( ) method is used to remove the item from the list.
It takes one optional argument . The element being deleted
is returned by the method
DIFFERENCE between pop() and
remove()
The pop( ) method removes an
individual item (from the right most
end  by default) or the
value/element present at the index
number mentioned in the parameter
and returns it. Whereas remove( )
searches the first occurrence of the
item and removes it from the list

Functions/
methods
remove(), pop(),
max(), sum(),clear()
 Lists Slicing;
 Nested lists;
minimum, mean
Functions / Methods on LIST- reverse()
reverse( ) method,
reverses the items of the list.
This doesn’t create a new list.
It takes no argument and return no list.
Reverses the list ‘in place’ and does not
return anything.
CONTENTS

Functions/
methods
extend(),
sum() , clear()
 Lists Slicing;
 Nested lists;
minimum, mean
Functions / Methods on LIST- sort()
sort( ) method,
sort( ) method and sort(reverse=True ) sorts or
orders the items of the list, by default in increasing order.
sort(reverse=True ) for getting the list in decreasing order
CONTENTS
NOTE: The sort( ) method
won’t be able to sort the
values of a list if it contains
complex numbers/tuple
/ mixed datatype as its
elements.

Functions/
methods
extend(),
sort(),min(),
max(), sum(),
clear()
 Lists Slicing;
 Nested lists;
minimum, mean
min( ) method,
Returns the minimum out of the elements/values/items of
the given List
CONTENTS
Functions / Methods on LIST- min(),max(),sum()
sum( ) method,
Returns the sum of all the values/elements/items of the
given List.
max( ) method,
Returns the maximum out of the elements/values/items of
the given List

Functions / Methods on LIST- min(),max(),sum() contd..
A List with
mixed data
type cannot
return values
for the min,
max and
sum
functions.
List of string . Maximum
and Minimum is done on
the basis of the ASCII
values of the characters
from the beginning.
Eg. ‘A’=65, ‘a’ = 97, ‘b’=98
and so on

Functions/
methods
extend(),
sort(),min(), max(), sum() ,
clear()
 Lists Slicing;
 Nested lists;
minimum, mean
Functions / Methods on LIST- clear()
clear( ) method,
removes all the items from the list and
the list becomes empty after executing
this function.
CONTENTS

LIST slicing
L[start:stop] creates a list slice out of list L with elements falling between
indexes start and stop, not including value at the stop index.
L[start:stop:step] creates a list slice out of list L with elements falling
between indexes start and stop, not including value at the stop index, and skipping
step elements in between.
B A C K W A R D I N D E X D I R E C T I O N
K N O W P Y T H O N B Y T E S
F O R W A R D I N D E X D I R E C T I O N
-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
NOTE: In absence of any start, stop, step values, we have Default start index as the beginning,
stop index as the last index and step value as +1.

-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
LIST slicing
Start index 3, stop index is (10-1=9)
Start index 5, stop index is 50 which is beyond the last index in forward
direction. Hence, it will stop at the last index
Start index -4(backward), stop index is (6-1=5 (forward)). Here, it is
not getting any value in the range, hence empty.
Start index -4(which is ‘Y’ as per the backward index,) stop index is 25
which is beyond the last index. Hence, it will stop at the last index.
Start index 10, stop index is 30 which is beyond the
last index in forward direction. Hence, it will stop at
the last index
Start index -10(which is ‘Y’ as per the backward index,) stop index is 12-1=11
(forward indexing). Hence, it will stop at the (stop index-1)., ‘Y’ is at 11 index no.

-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Start index -20(which is beyond backward index,) stop
index is -5 which takes value till (-5-1=-6). Here, -6 is ‘N’.
Start index 1, stop index is 13 (till 13-1=12),step value
is 2 in forward direction. Hence, it will fetch/take
alternate elements with a skip of 1 value in between
Start index -3(backward), stop index is -12(backward). Here, it is not getting
any value in the range as no step value mentioned in reverse. Hence empty.
Start index -12(which is ‘W’ as per the backward index,)
stop index is -3 (which takes values till index -3-1= -4)
Start index -3(backward), stop index is -12(backward). Here, it is getting
value in the range as step value is -1 mentioned in reverse.
TRY TO UNDERSTAND YOURSELF. A task for you.
Also write the slice for List to get the output as
LIST SLICING contd.
Default start and stop is beginning and end index of the list. Here, step is 3.
?

CONTENTS
Lists Intro
 Lists Slicing;
 Nested lists;
minimum, mean
NESTED LISTS
Nested List 1 Nested List 2
Enclosing List
Note: Denoting Nested elements
using Index nos.
M[0]  10
M[1]  [15,30]
M[1][0]15
M[1][1]30
M[2] *80,’Mask’,60+
M[2][0]80
M[2][1]‘Mask’
M[2][2]60

Lists Intro
Operations on
a list
Functions/
methods
 Lists Slicing;
 Nested lists;
finding
the
maximum
, minimum, mean
 linear search
on list
 counting the
frequency
Program to find the MAXIMUM element from a list of element along
with its index in the list without using max() library function
OUTPUT
CONTENTS

Lists Intro
Operations on a
list
Functions/
methods
 Lists Slicing;
 Nested lists;
finding
the
minimum,
maximum , mean
 linear search
on list
 counting the
frequency
Program to find the MINIMUM element from a list of element along
with its index in the list without using min() library function
CONTENTS
OUTPUT

Lists Intro
Operations on a
list
Functions/
methods
 Lists Slicing;
 Nested lists;
finding
the mean,
maximum,
minimum
 linear search
on list
 counting the
frequency
Program to find the MEAN (AVERAGE) of all the elements of
the list
CONTENTS
OUTPUT

CONTENTS
Lists Intro
Operations on a
list
Functions/
methods
 Lists Slicing;
 Nested lists;
finding the
mean, maximum,
minimum
 linear
search on
list
 counting the
frequency OUTPUT
Program to search an element in the List (LINEAR SEARCH)

CONTENTS
Lists Intro
Operations on a
list
Functions/
methods
 Lists Slicing;
 Nested lists;
finding the
mean, maximum,
minimum
 linear search
on list

counting
the
frequency
OUTPUT
Program to count frequency (/no. of times of occurrence) of an element in the List
(FREQUENCY COUNT)

Bibliograhy and References
• Google
• Wikipedia
• XI Computer Science , By Sumita Arora,
Dhanpat Rai Publication 2020 Edition
• XI Informatics Practices , By Sumita Arora,
Dhanpat Rai Publication 2020 Edition

Programming is an ART….
Add your colours to it and make your own

FINAL revised LIST in Python.pdf

More Related Content

What's hot (20)

Similar to FINAL revised LIST in Python.pdf (20)

Recently uploaded (20)

FINAL revised LIST in Python.pdf