Tuples

Tuple is an immutable collection of elements (may be of same or different types), which is indexed by a 0-based integer. A 2-tuple can represent a point in 2-D plane, or a 3-Tuple can represent a point in 3-D plane.

Creating Tuples

Creating an empty tuple

x = ()  # () denotes a tuple type
       # or
       x = tuple()

Creating list with some initial elements

x = (2,3,0,'g')



In [1]:

    
x = (2,3)



In [2]:

    
x









    Out[2]:





(2, 3)



In [3]:

    
x = (2,)  # x = (2) assigns int 2 to x. To make it a tuple, a comma is appended



In [4]:

    
x









    Out[4]:





(2,)



In [5]:

    
x + (1,2)









    Out[5]:





(2, 1, 2)

Tuples are immutable. So once a tuple is created, its contents are permanent unless it is reassigned with another tuple.

Tuples can also be Indexed and Sliced like lists



In [6]:

    
x









    Out[6]:





(2,)



In [7]:

    
x = x + (1,3,4)   # Reassignment



In [8]:

    
x









    Out[8]:





(2, 1, 3, 4)



In [9]:

    
x[1]









    Out[9]:





1



In [10]:

    
x[2:5]









    Out[10]:





(3, 4)



In [11]:

    
x[::-1]









    Out[11]:





(4, 3, 1, 2)

Operations on Tuples

Since tuples are immutable, operations do not modify the original tuple

Here are some of the operations on list. They are member functions of class tuple. If x is a tuple,

x.index(ele) - searches for the given element from the start of the list and returns its index. Throws a ValueError if the element does not appear (use in to check without a ValueError).
x.count(ele) - counts the number of occurances of ele in x

Membership operator in is also supported



In [12]:

    
x









    Out[12]:





(2, 1, 3, 4)



In [13]:

    
2 in x









    Out[13]:





True



In [14]:

    
x.count(2)









    Out[14]:





1



In [17]:

    
x.index(3)









    Out[17]:





2

Using a list of tuples, one can model a collection of points in space