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