Python Dictionary – Advanced. With YouTube video.

Posted on November 19, 2023 by

Some time ago, I wrote an article about defaultdict in Python here – vitoshacademy.com/python-defaultdict-object-or-how-to-avoid-the-key-error. Now, I have decided to make a video about it and increase the scope with standard dictionary functions and an advanced class, that checks whether the value is recorded under a key with string or integer and returns the value, if it is found under any of these.

A horse from the mine museum of Pernik, Bulgaria

So, let’s start. We can have the following functions to a dictionary:

General functions of a dictionary

my_dict.items()
- list(my_dict.items())
- list(my_dict.items())[2:]
my_dict.keys()
- list(my_dict.keys())
my_dict.get(key, value-if-key-not-present)
my_dict.pop(key)
my_dict.popitem()
- # this one pops an item, that should be somehow random, as the dictionaries are unordered
my_dict.update({key:value})
- if the key is not found, a new key-value pair is written
- if the key is found, its value is overwritten
my_dict.fromkeys(abcdef)
- {'a': None, 'b': None, 'c': None, 'd': None, 'e': None, 'f': None}
my_dict.fromkeys(‘abcdef’, 5)
- {'a': 5, 'b': 5, 'c': 5, 'd': 5, 'e': 5, 'f': 5}

Just a bit about defaultdict

Additionally, once good solution to resolve defaultdict issues is to make sure that it targets a simple function. Like this:

from collections import defaultdict

def default_dict_result():
    return 'No such value in the dictionary, sorry.'

my_new_dict = defaultdict(default_dict_result)
print(my_new_dict['Germany'])

from collections import defaultdict

def default_dict_result():

return 'No such value in the dictionary, sorry.'

my_new_dict = defaultdict(default_dict_result)

print(my_new_dict['Germany'])

What if we need to not care about strings and integers in a dictionary?

# Code is from EXERCISE 42 - FlexibleDict - Python Workout - Author Lerner - Manning
# https://www.manning.com/books/python-workout

class FlexibleDict(dict):
    def __getitem__(self, key):
        try:
            if key in self:
                pass
            elif str(key) in self:
                key = str(key)
                print('in the dictionary it is a str!')
            elif int(key) in self:
                key = int(key)
                print('in the dictionary it is a int!')
        except ValueError:
            pass
        return dict.__getitem__(self, key)

# Code is from EXERCISE 42 - FlexibleDict - Python Workout - Author Lerner - Manning

# https://www.manning.com/books/python-workout

class FlexibleDict(dict):

def __getitem__(self, key):

try:

if key in self:

pass

elif str(key) in self:

key = str(key)

print('in the dictionary it is a str!')

elif int(key) in self:

key = int(key)

print('in the dictionary it is a int!')

except ValueError:

pass

return dict.__getitem__(self, key)

The idea here, is that in general, this will work as a normal dictionary. Unless you are looking for [‘1’] and the only present key is [1]. Or the other way around. Then this dictionary implementation would save you some seconds of debugging. And would probably create hours of debugging later, but who knows…

The YouTube video is this one: