How to Set Default Dictionary Python Value ?

Dictionary is special data type in python which contains the data in the form of name : value pair. It stores the mapping between names and values. Here, the value of the dictionary can be any valid data type of the python. In this post, we check, how to set default dictionary python value.

If we are storing the mapping of entities in the dictionary, the mapping can be too large. Actual what we need is a just subset of it.

Let’s make the thing simple. Take the instance. It will be easy to understand.

Suppose we are maintaining the capitals of countries enrolled in BRICS association. The mapping of countries involved in BRICS association is mapped with their capitals.

Our aim is to find the capital of the country if it is enrolled in BRICS association. If it is not listed in the community, it returns as ‘Country is not listed in BRICS’

dictBRICMap is dictionary storing BRICs country as name and its capital as dictionary value

>>>> dictBRICMap = {'Brazil':'Brasília', 'Russia':'Moscow', 'India':'New Delhi', 
'China':'Beijing', 'South Africa':'Cape Town'}

The easiest way to find the capital of country enrolled in BRICs is as follows.

>>>> print dictBRICMap['India']
'New Delhi'

We can also find it by calling dictionary function dict.get(‘key’) as follows.

>>>> print dictBRICMap.get('India')
'New Delhi'

But if we provide a key which is not present in the dictionary, it throws an error as follows.

>>>> print dictBRICMap.get('Japan')
Traceback (most recent call last):
File "", line 1, in 
KeyError: 'japan'

Simple Code to Set Default Dictionary Python Value

To tackle with this, we can provide the default value for the key. If the country does not match with any of the keys in the dictionary, it takes default dictionary python value as follow.

>>>> print dictBRICMap.get('Japan','Country not listed in BRICs')
'Country not listed in BRICs'

Many times it is not possible to provide all the dictionary values. Taking default dictionary python value is good provision to tackle with invalid dictionary key. You can also prompt as ‘Key not present in the dictionary’ if the user provides ‘invalid key’.