tuples

You can see that tuples are very much like a list that cannot be changed, and use the round braces/brackets.  Because they are immutable (unchangeable) there are much fewer methods associated with tuples than with lists, or even with strings.  Strings are also immutable, but contain a specific type, whereas tuples can contain many types of objects.  We might typically use tuples to define RGB colours, since they do not change e.g. RED is (255, 0 , 0).

Other collections can be converted to a tuple using the builtin function tuple().  Many of the usual functions and methods that are also implemented for strings and lists will seem familiar- but remember that these methods are implemented differently under the hood for tuples- methods are NOT shared between classes.

Here are some examples of common functions and methods you might use, or try to use.

>>> my_list = [1, 2.4, "Jimmy"]

>>> tuple(my_list)  # convert list to tup

(1, 2.4, 'Jimmy')

>>> word = 'hello'

>>> tuple(word)    # convert str to tup

('h', 'e', 'l', 'l', 'o')

>>> t1 = (1, 2, 3, 4, 5)  # instantiate a tuple

>>> t2 = (2, 4, 4, 6, 8)  # instantiate another tuple

# common functions

>>> len(t1)  # get the number of elements in the tuple

5

>>> max(t2)  # find the highest value inside the tuple

8

>>> min(t2)  # find the lowest value inside the tuple

2

# methods and indexing

>>> t2.count(4)  # fins the number of instances of (obj w/value) inside the tuple

2

>>> t2[-1]  # use indexing

8

>>> t1[2] = 7  # tuples are immutable

Traceback (most recent call last):

  File "<pyshell>", line 1, in <module>

TypeError: 'tuple' object does not support item assignment

>>> t2.index(6)  # find the index of the value inside the tuple

3

>>> t2.index(3)  # trying to get the index of something not there causes an error

Traceback (most recent call last):

  File "<pyshell>", line 1, in <module>

ValueError: tuple.index(x): x not in tuple

>>> # this could be handled by first checking if obj is in the tuple

>>> # You may use the in keyword with tuples

>>> t1.append(9)  # tuples are immutable

Traceback (most recent call last):

  File "<pyshell>", line 1, in <module>

AttributeError: 'tuple' object has no attribute 'append'

>>> t1 = t1 + t2  # tuples are immutable, but this just creates a new one and overwrites the object that t1 is pointing to.

>>> t1

(1, 2, 3, 4, 5, 2, 4, 4, 6, 8)

>>> t1.sort()  # tuples are immutable

Traceback (most recent call last):

  File "<pyshell>", line 1, in <module>

AttributeError: 'tuple' object has no attribute 'sort'