Python programming UNIT III-Part-2.0.pptx

Government Arts and Science College
Tittagudi – 606 106
Department of Computer Science
Python Programming
Python Programming
Dr. S. P. Ponnusamy
Assistant Professor and Head
1
Unit – 3

Python Programming
Syllabus
• UNIT III
Tuples – creation – basic tuple operations – tuple() function –
indexing – slicing – built-in functions used on tuples – tuple
methods – packing – unpacking – traversing of tuples –
populating tuples – zip() function - Sets – Traversing of sets –
set methods – frozenset.
–.

Python Programming
3
Tuples

Python Programming
Tuples - Introduction
 Tuple is a collection of objects that are ordered, immutable, finite, and
heterogeneous (different types of objects).
 The tuples have fixed sizes.
 Tuples are used when the programmer wants to store multiples of
different data types under a single name.
 It can also be used to return multiple items from the function.
 The elements of the tuple cannot be altered as strings (both are
immutable).

Python Programming
Tuples - Creation
 The tuple is created with elements covered by a pair of opening and
closing parenthesis.
 An empty tuple is created with empty parenthesis.
 The individual elements of tuples are called "items."
>>> myTuple = (1, 2.0, 4.67, "Chandru", 'M')
>>> myTuple
(1, 2.0, 4.67, 'Chandru', 'M')
>>> myTuple=()
>>> myTuple
()
>>>type(myTuple)
<class 'tuple'>

Python Programming
Tuples - Creation
 Covering the elements in parenthesis is not mandatory.
 That means, the elements are assigned to tuples with comma separation
only.
>>> myTuple = 1, 2.0, 4.67, "Chandru", 'M'
>>> myTuple
(1, 2.0, 4.67, 'Chandru', 'M’)

Python Programming
Tuples - Creation
 A tuple with single item creation is problem in Python as per the above
examples.
 A single item covered by parenthesis is considered to be its own base
type.
>>> myTuple=(8)
>>> myTuple
8
>>> type(myTuple)
<class 'int'>
>>> myTuple =("u")
>>> myTuple
'u'
type(myTuple)
<class 'str'>

Python Programming
Tuples - Creation
 A tuple with a single item can be created in a special way.
 The elements should be covered with or without parenthesis, but an
additional comma must be placed at the end.
>>> myTuple=(8,)
>>> myTuple
(8,)
>>> type(myTuple)
<class 'tuple'>
>>> myTuple=("God",)
>>> myTuple
('God',)
>>> type(myTuple)
<class 'tuple'>
>>> myTuple=8,
>>> myTuple
(8,)

Python Programming
10
Basic Tuple operations

Python Programming
Tuples operations - Concatenation
 The tuple concatenation operation is done by the "+" (plus) operator.
 Two or more tuples can be concatenated using the plus operator .
>>> myTuple1=(1,2.4,"ABC")
>>> myTuple2=(111.23,-12,"xyz",23)
>>> myTuple3=myTuple1+myTuple2
>>> myTuple3
(1, 2.4, 'ABC', 111.23, -12, 'xyz', 23)
>>> (12,"University",33.8)+(23,345.12)
(12, 'University', 33.8, 23, 345.12)

Python Programming
Tuples operations - Repetition
 You must be careful when you apply tuple concatenation.
 The other type of value cannot be concatenated with tuple literals using
the concatenation operator.
 If you try this, the interpreter will raise a TypeError message.
>>>(12,"University",33.8)+ 8
Traceback (most recent call last):
File "<pyshell#7>", line 1, in <module>
(12,"University",33.8)+ 8
TypeError: can only concatenate tuple (not "int") to
tuple

Python Programming
Tuples operations - Repetition
 The given tuple is repeated for the given number of times using the ‘*’
(multiplication) operator.
 The operator requires the tuple as the first operand and an integer value
(the number of times to be repeated) as the second operand.
>>> (1,2,3,"Apple")*3
(1, 2, 3, 'Apple', 1, 2, 3, 'Apple', 1, 2, 3, 'Apple')
>>> (1,2,3,"Apple")*2 +(3,5,23.1)
(1, 2, 3, 'Apple', 1, 2, 3, 'Apple', 3, 5, 23.1)
 Tuple concatenation can be applied along with the tuple repetition.

Python Programming
Tuples operations – Member operator - in
 The member operators are used to check the existence of the given
value in the tuple or not.
 The operator ‘in’ returns True when the given value exists in a tuple, else
it returns False. It is a binary operator.
>>> myTuple1=(111.23,-12,"xyz",23)
>>> 23 in myTuple1
True
>>> 42 in myTuple1
False
>>> "xyz" in myTuple1
True

Python Programming
Tuples operations – Member operator - not in
 The operator ‘not in’ returns True when the value does not exist in the
tuple, else it returns False.
 It works opposite to the ‘in‘ operator.
>>> myTuple1=(111.23,-12,"xyz",23)
>>> 42 not in myTuple1
True
>>> 23 not in myTuple1
False

Python Programming
Tuples operations – Comparison
 The comparison operations on tuples are done with the help of the
relational operators ==. !=, <, >, <=, >=.
 These operators can be applied only to tuple literals and variables.
 Python compares the tuples' values one by one on both sides.
>>> myTuple1=(111.23,-12,"xyz",23)
>>> myTuple2=(111.23,-12,"xyz",23)
>>> myTuple1==myTuple2
True
>>> myTuple1>myTuple2
False
>>> myTuple2=(123,-12,34)
>>> myTuple1<myTuple2
True

Python Programming
17
Tuple() function

Python Programming
Tuples function – tuple()
 It is a built-in function used to create a tuple or convert an iterable
object into a tuple.
 The iterable objects are list, string, set, and dictionary.
>>> tuple("University") #converts string into tuple
('U', 'n', 'i', 'v', 'e', 'r', 's', 'i', 't', 'y')
>>> tuple([1,2,3,"xyz"]) #converts list into tuple
(1, 2, 3, 'xyz')

Python Programming
Tuples function – tuple()
>>> s1={1,2,3,4}
>>> t1=tuple(s1) # converting set into tuple
>>> t1
(1, 2, 3, 4)
>>> tuple({1:"Apple",2:"Mango"}) #converts dictionary
into tuple
(1, 2)
>>> d1={1:"Apple",2:"Mango"} #converts dictionary items
into tuple
>>> tuple(d1.items())
((1, 'Apple'), (2, 'Mango'))

Python Programming
20
Indexing and slicing

Python Programming
Indexing
 The tuple elements can be accessed by using the indexing operator.
 You can access individual elements by single indexing.
 The Python allows both positive and negative indexing on tuples.
 The positive indexing starts at 0 and ends at n-1, where n is the length of
the tuple.
 The negative indexing starts at -1 and ends at -n.
 The positive indexing follows a left-to-right order, whereas the negative
indexing follows a right-to-left order.

Python Programming
Indexing
>>> myTuple=(11,23.5,-44,'xyz')
>>> myTuple[2]
-44
>>> myTuple[0]
11
>>> myTuple[-3]
23.5
>>> myTuple[3]
'xyz'

Python Programming
Slicing
 A subset or slice of a tuple can be extracted by using the index operator
as in a string.
 The index operator takes three parameters, which are separated by a
colon.
 The parameters are the desired start and end indexing values as well as
an optional step value.

Python Programming
Indexing
>>> myTuple[-3:-1]
(78.98, 'xyz')
>>> myTuple[-4:]
(-34, 78.98, 'xyz', 8)
>>> myTuple[:-2]
(23, -34, 78.98)
>>> myTuple[:]
(23, -34, 78.98, 'xyz', 8)
>>>
(23, -34, 78.98, 'xyz', 8)
>>> myTuple=(23,-34,78.98,"xyz",8)
>>> len(myTuple)
5
>>> myTuple[1:3]
(-34, 78.98)
>>> myTuple[:4]
(23, -34, 78.98, 'xyz')
>>> myTuple[2:]
(78.98, 'xyz', 8)

Python Programming
25
Built-in Functions

Python Programming
Built-in Functions
Function Description
len(tuple) Gives the total length of the tuple.
max(tuple) Returns item from the numerical tuple with max value.
min(tuple) Returns item from the numerical tuple with min value.
sum(tuple)
Gives the sum of the elements present in the numerical
tuple as an output
tuple(seq) Converts an iterable object into tuple.
(already discussed in section 6.4)
sorted(tuple) Returns a sorted list as an output of a numerical tuple in
ascending order

Python Programming
27
Tuple Methods

Python Programming
Methods
Function Description
tuple.count(value) Returns the number of times a specified value occurs in a tuple
if found. If not found, returns 0.
tuple.index(value) Returns the location of where a specified value was found after
searching the tuple for it. If the specified value is not found, it
returns error message.

Python Programming
Methods
>>> myTuple1=(13,-34,88,23.5,78,'xyz',88)
>>> myTuple1.count(13)
1
2
0
>>> myTuple1.index(78)
4
>>> myTuple1.index(103)
Traceback (most recent call last):
File "<pyshell#24>", line 1, in <module>
myTuple1.index(103)
ValueError: tuple.index(x): x not in tuple

Python Programming
30
End

Python programming UNIT III-Part-2.0.pptx

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