Python Collections (Arrays)
There are four collection data types in the Python programming language:
- List is a collection which is ordered and changeable. Allows duplicate members.
- Tuple is a collection which is ordered and unchangeable. Allows duplicate members.
- Set is a collection which is unordered and unindexed. No duplicate members.
- Dictionary is a collection which is unordered, changeable and indexed. No duplicate members.
When choosing a collection type, it is useful to understand the properties of that type. Choosing the right type for a particular data set could mean retention of meaning, and, it could mean an increase in efficiency or security.
List
A list is a collection which is ordered and changeable. In Python lists are written with square brackets.
Example
Create a List:
thislist = ["apple", "banana", "cherry"] print(thislist)
Output
Access Items
You access the list items by referring to the index number:
Example
Print the second item of the list:
thislist = ["apple", "banana", "cherry"] print(thislist[1])
Output
Change Item Value
To change the value of a specific item, refer to the index number:
Example
Change the second item:
thislist = ["apple", "banana", "cherry"] thislist[1] = "blackcurrant" print(thislist)