Basic Data Structures
As a general rule, data structures are objects that contain a possibly large number of other
objects. Among those that Python provides as built-in structures are:
tuple
A collection of arbitrary objects; only a few methods available
list
A collection of arbitrary objects; many methods available
dict
A key-value store object
set
An unordered collection object for other unique objects
Tuples
A tuple is an advanced data structure, yet it’s still quite simple and limited in its
applications. It is defined by providing objects in parentheses:
In [ 37 ]: t = ( 1 , 2.5, ‘data’)
type(t)
Out[37]: tuple
You can even drop the parentheses and provide multiple objects separated by commas:
In [ 38 ]: t = 1 , 2.5, ‘data’
type(t)
Out[38]: tuple
Like almost all data structures in Python the tuple has a built-in index, with the help of
which you can retrieve single or multiple elements of the tuple. It is important to
remember that Python uses zero-based numbering, such that the third element of a tuple
is at index position 2:
In [ 39 ]: t[ 2 ]
Out[39]: ‘data’
In [ 40 ]: type(t[ 2 ])
Out[40]: str
ZERO-BASED NUMBERING
In contrast to some other programming languages like Matlab, Python uses zero-based numbering schemes. For
example, the first element of a tuple object has index value 0.
There are only two special methods that this object type provides: count and index. The
first counts the number of occurrences of a certain object and the second gives the index
value of the first appearance of it:
In [ 41 ]: t.count(‘data’)
Out[41]: 1
In [ 42 ]: t.index( 1 )
Out[42]: 0
tuple objects are not very flexible since, once defined, they cannot be changed easily.
Lists
