Python Tuples

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How to work with Python tuples

Python tuple is an immutable, ordered sequence of elements.

Python tuples are similar to Python list, except that we can't change the elements in a tuple. If you don't know how python list works, please go through this Python Lists

Python tuples are,
  • Immutable (cannot change the items of a tuples)
  • Ordered, follows insertion order. Can be accessed by index

How to create a Python tuple

# creates an empty tuple

t = ()
t1 = tuple()

# creating a tuple with some data

t = (1, 2, 3)
t1 = (1, 'hello', 4.5, [1, 2, 3])

# a tuple can have a tuple, list or dictionary as its item

t = (1, 2, ['a', 'b'], (1.5, 2.5), {1: 'x', 2: 'y'})
Special case with one element in a Python tuple, 
t = ('one_element')
print(type(t))

# output : class 'str'
# even though the element is inside the `()` it will be treated as String.

Please put a `,` after the element, then only Python will treat it as a Python tuple.

t = ('one_element',)
print(type(t))

# output : class 'tuple'

How to access elements in a Python tuple

Python tuples can be accessed using index. 
t = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

print(t[0])

# output : 1

print(t[-1])

# output : 10

print(t[100])

# output : IndexError: tuple index out of range


**When you try to access an element with index out of range. Python will trow an error.

Slicing in Python tuples

t = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

print(t[0:])

# output : (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

print(t[-1::-1])

# output : (10, 9, 8, 7, 6, 5, 4, 3, 2, 1)

print(t[2:5])

# output : (3, 4, 5)

Modifying the elements of a tuple

Ohh...! Python tuples are immutable. Can I change the elements of a tuple??
Yes, elements inside a tuple can be mutable as long as the element is mutable. Confused?? Lets see an example. 
t1 = ('first', 'x', 'y', [1, 2, 3])

t1[0] = 'modified'

# output : TypeError: 'tuple' object does not support item assignment
In the above case Python tuple doesn't allow us to change the item because strings are immutable. Lets see another case. 
t1 = ('first', 'x', 'y', [1, 2, 3])

t1[3][1] = 'modified'

print(t1)

# output : ('first', 'x', 'y', [1, 'modified', 3])
In this case Python tuple allowed us to modify the value inside a list. Because list is mutable. So to conclude, if the item inside a Python tuple is mutable then we can modify that value inside the mutable item. Like the case of a list that we did in the above code snippet.

Deleting the items from a tuple

Items from a tuple cant be deleted because Python tuple is immutable. We can delete the entire tuple. 
t = (1, 2, 3)

del t

**If you try to access it after deletion, an error will be thrown.

Other useful functions of a Python tuple

t = (4, 2, 3, 4, 5, 6, 7, 4, 9, 10)

print(t.count(4))

# output : 3
# prints the no of times the given element is found in the tuple

print(t.index(5))

# output : 4
# prints the index of the first occurence of the given element

print(5 in t)

# output : True
# Returns True if the element is present in the tuple

print(5 not in t)

# output : False

print(len(t))

# output : 10

new_t = sorted(t)
print(new_t)

# output : [2, 3, 4, 4, 4, 5, 6, 7, 9, 10]
# remember returns a sorted list not a tuple

print(max(t))

# output : 10

print(min(t))

# output : 2

print(sum(t))

# output : 54

** mathematical functions like min, max and sum can be applied on tuples with numbers only

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