Overview of list and set¶
There are 4 types of collections in Python. While list and set fundamentally contain homogeneous elements, dict and tuple contain heterogeneous elements.* Homogeneous means of same type.
- Examples of collections with homogeneous elements.
- Collection of employees –
list - Collection of unique employees –
set - Collection of integers –
list - Collection of unique integers –
set
- Collection of employees –
- Based up on the requirement we should use appropriate type of collection.
list- Group of homogenous elements.
- There can be duplicates in the
list. listcan be created by enclosing elements in[]– example[1, 2, 3, 4].- Empty
listcan be initialized using[]orlist().
set- Group of homogenous elements
- No duplicates allowed in the
set. Even if you add same element more than once, such elements will be ignored. setcan be created by enclosing elements in{}– example{1, 2, 3, 4}.- Empty
setcan be initialized usingset(). We cannot initialize empty set using{}as it will be treated as emptydict.
listandsetcan be analogous to Table with columns and rows whiledictandtuplecan be analogous to a row with in a table.listcan hold duplicate values whilesetcan only hold unique values.- If you want to have a row with column names then we use
dictotherwise we usetuple. - We will deep dive into all types of collections to get better understanding about them.
In [1]:
l = [1, 2, 3, 3, 4, 4]
In [2]:
l
Out[2]:
[1, 2, 3, 3, 4, 4]
In [3]:
l = []
In [4]:
l
Out[4]:
[]
In [5]:
type(l)
Out[5]:
list
In [6]:
l = list()
In [7]:
l
Out[7]:
[]
In [8]:
s = {1, 2, 3, 3, 4, 4}
In [9]:
s
Out[9]:
{1, 2, 3, 4}
In [10]:
type(s)
Out[10]:
set
In [11]:
s = set() # Initializing empty set
In [12]:
s
Out[12]:
set()
In [13]:
s = {} # s will be of type dict
In [14]:
type(s)
Out[14]:
dict