Python: Tuple Data Structure

1. The tuple is exactly the same as the List except that it is immutable. i.e once we create a Tuple object, we cannot perform any changes in that object. Hence Tuple is the Read Only version of the List.
2. If our data is fixed and never changes then we should go for Tuple.
3. Insertion Order is preserved
4. Duplicates are allowed
5. Heterogeneous objects are allowed.
6. We can preserve insertion order and we can differentiate duplicate objects by using an index. Hence index will play a very important role in Tuple also. Tuple support both +ve and -ve index. +ve index means forward direction(from left to right) and -ve index means backward direction(from right to left)
7. We can represent Tuple elements within Parenthesis and with a comma separator. Parenthesis are optional but recommended to use.

Eg:

1. t=10,20,30,40 
2. print(t) 
3. print(type(t)) 
4. 
5. Output
6. (10, 20, 30, 40) 
7. <class 'tuple'> 
8. 
9. t=() 
10. print(type(t)) # tuple 

Tuple creation:

1. t=()

 creation of empty tuple

2. t=(10,)

 t=10,

 creation of single valued tuple ,parenthesis are optional,should ends with comma

3. t=10,20,30

 t=(10,20,30)

 creation of multi values tuples & parenthesis are optional

4. By using tuple() function:

1. list=[10,20,30] 
2. t=tuple(list) 
3. print(t) 
4. 
5. t=tuple(range(10,20,2)) 
6. print(t)

Accessing elements of tuple:

We can access either by index or by slice operator

1. By using index:

1. t=(10,20,30,40,50,60) 
2. print(t[0]) #10 
3. print(t[-1]) #60 
4. print(t[100]) IndexError: tuple index out of range 

2. By using slice operator:

1. t=(10,20,30,40,50,60) 
2. print(t[2:5]) 
3. print(t[2:100]) 
4. print(t[::2]) 
5. 
6. Output
7. (30, 40, 50) 
8. (30, 40, 50, 60) 
9. (10, 30, 50) 

Tuple vs immutability:

Once we creates tuple,we cannot change its content.

Hence tuple objects are immutable.

 Eg:

t=(10,20,30,40)
t[1]=70 TypeError: 'tuple' object does not support item assignment

Mathematical operators for tuple:

We can apply + and * operators for tuple

1. Concatenation Operator(+):

1. t1=(10,20,30) 
2. t2=(40,50,60) 
3. t3=t1+t2 
4. print(t3) # (10,20,30,40,50,60) 

2. Multiplication operator or repetition operator(*)

1. t1=(10,20,30) 
2. t2=t1*3 
3. print(t2) #(10,20,30,10,20,30,10,20,30) 

Important functions of Tuple:

1. len()

 To return number of elements present in the tuple

 Eg:
 t=(10,20,30,40)
 print(len(t)) #4

2. count()

 To return number of occurrences of given element in the tuple

 Eg:
 t=(10,20,10,10,20)
 print(t.count(10)) #3

3. index()

 returns index of first occurrence of the given element.

 If the specified element is not available then we will get ValueError.

 Eg:
 t=(10,20,10,10,20)
 print(t.index(10)) #0
 print(t.index(30)) ValueError: tuple.index(x): x not in tuple

4. sorted()

 To sort elements based on default natural sorting order

1. t=(40,10,30,20) 
2. t1=sorted(t) 
3. print(t1) 
4. print(t) 
5. 
6. Output
7. [10, 20, 30, 40] 
8. (40, 10, 30, 20) 

We can sort according to reverse of default natural sorting order as follows

t1=sorted(t,reverse=True)

print(t1) [40, 30, 20, 10]

5. min() and max() functions:

These functions return min and max values according to default natural sorting order.

Eg:

1. t=(40,10,30,20) 
2. print(min(t)) #10 
3. print(max(t)) #40 

6. cmp():

It compares the elements of both tuples.

If both tuples are equal then returns 0

If the first tuple is less than second tuple then it returns -1

If the first tuple is greater than second tuple then it returns +1

Eg:

1. t1=(10,20,30) 
2. t2=(40,50,60) 
3. t3=(10,20,30) 
4. print(cmp(t1,t2)) # -1 
5. print(cmp(t1,t3)) # 0 
6. print(cmp(t2,t3)) # +1

Tuple Packing and Unpacking:

We can create a tuple by packing a group of variables.

Eg:

a=10
b=20
c=30
d=40
t=a,b,c,d
print(t) #(10, 20, 30, 40)

Here a,b,c,d are packed into a tuple t. This is nothing but tuple packing.

Tuple unpacking is the reverse process of tuple packing

We can unpack a tuple and assign its values to different variables

Eg:

1. t=(10,20,30,40) 
2. a,b,c,d=t 
3. print("a=",a,"b=",b,"c=",c,"d=",d) 
4. 
5. Output
6. a= 10 b= 20 c= 30 d= 40 

Tuple Comprehension:

Tuple Comprehension is not supported by Python.

 t= ( x**2 for x in range(1,6))

Here we are not getting tuple object and we are getting generator object.

1. t= ( x**2 for x in range(1,6)) 
2. print(type(t)) 
3. for x in t: 
4. print(x) 
5. 
6. Output
7. D:\Python_classes>py test.py 
8. <class 'generator'> 
9. 1 
10. 4 
11. 9 
12. 16 
13. 25

Differences between List and Tuple:

List and Tuple are exactly same except small difference: List objects are mutable where as Tuple objects are immutable.

In both cases insertion order is preserved, duplicate objects are allowed, heterogenous objects are allowed, index and slicing are supported.

List	Tuple
1) List is a Group of Comma separeated Values within Square Brackets and Square Brackets are mandatory.   Eg: i = [10, 20, 30, 40]	1) Tuple is a Group of Comma separeated Values within Parenthesis and Parenthesis are optional.   Eg: t = (10, 20, 30, 40)  t = 10, 20, 30, 40
2) List Objects are Mutable i.e. once we creates List Object we can perform any changes in that Object.   Eg: i[1] = 70	2) Tuple Objeccts are Immutable i.e. once we creates Tuple Object we cannot change its content.  t[1] = 70 => ValueError: tuple object does not support item assignment.
3) If the Content is not fixed and keep on changing then we should go for List.	3) If the content is fixed and never changes then we should go for Tuple.
4) List Objects can not used as Keys for Dictionries because Keys should be Hashable and Immutable.	4) Tuple Objects can be used as Keys for Dictionries because Keys should be Hashable and Immutable.

"Python Tuple Data Structure"

"Python Tuple Underlying Data Structure"

"Python Data Structure Tuple Dict"

"Python Tuple With Names"

"Python * Before Tuple"

"Python Data Structure Methods"

"Python Recursive Data Structure"

"Python Tuple Multiple Types"