Dictionaries in python are used to store key - value pairs and they may have non-numeric indexes.
The dict keyword is used to create dictionaries:
Data can be inserted by specifying certain key and value.
Example:
In this example, 2 records have been inserted.
Values can be accessed via their keys.
Let's look at the following example:
Output:
The key-value pair for Coke is set at line 3
and accessed at line 6.
Accessing key that's not set in the array results in KeyError.
Let's look at the following example:
The dictionary doesn't contain any Coke key, so drinks["Coke"] causes an exception.
Let's have a program in which students scores are stored in dictionary and printed afterwards.
Output:
The following code is suitable for Python 3 but if you use Python 2, you need to replace
items() with iteritems().
That's done via the del keyword like in this example:
If unexisting key is attempted to be removed (like del drinks['Juice'])
then a KeyError is thrown.
It can be done via the in keyword like in the following code:
Output:
Water key is not set thus Water is not printed.
Size is the count of the key-value pairs.
It can be accessed via the len function.
Let's look at this example:
Output:
4 records were inserted and 1 is deleted afterwards. This makes for 3 key-value pairs.