Operators and Methods for Dictionaries in Python

Very well presented and shows I am not the only one who can’t type and spell!

Great course!

What method[s] do you suggest for creating a large dict from a file?

Excellent presentation!

Cool thanks..

Would be nice to have included methods to mass load a dictionary (e.g. from a JSON file) or save dictionary values… Nevertheless, it was fine! Thanks!

Love it! this is basically an API call isn’t it?

It would be really helpful to have real world example of Dict and also to build dictionaries from some file

Great course.

Reading/Importing JSON data as dicitionary.

import json

jsonData = '[{"FirstName" : "Bob", "LastName" : "Johnson"}, {"FirstName": "Andrew", "LastName" : "Brown"}]'

# if you want to parse JSON file, use json.load() function instead
parsedJson = (json.loads(jsonData)) 

"""
parsedJson is stored as list
# whereas, each item within parsedJson list is stored as dictionary
"""
print(parsedJson)
print(type(parsedJson)) 
#print(type(parsedJson[0])) 

#Reading values from list, and then fetch FirstName, LastName from dictionaries
for x in parsedJson:
    print(x["FirstName"], x["LastName"])

The get method has None as default, this default can be changed.

Would be nice to discuss collections, DefaultDict, in Collections used to avoid key errors if you try and query a key that does not exist.

Thanks for the videos.

Excellent coverage of the basics of Dicts in Python. An advanced course with projects using them would be equally great.

Out of all the video instructors so far I enjoy your style the best. Calm, chill, takes time to explain things, and enjoyable to listen to. Props you to my man, I hope more comes from you.

Thanks Paul. Nice!

Objective and direct! Very useful!

You raced over restrictions so fast I had not idea what you meant.

Thank you for great course!

Superb course , thanks Paul

thanks Paul.....enough to make me going nicely....this is a great base really.....

A very informative course; thank you so much!

Very well explained, thanks.

From Python version 3.6 the .popitem() method is no longer a random function but simply returns and removes the last key:value pair in the dictionary. This is explained in another RP tutorial about dictionaries.

I think the .get() method returns a value and not a key as mentioned in the video. If the given key exists, its value is returned and if not then the default value.

my_dict = {'a': 1, 'b':2, 'c':3}
print(my_dict.get('d', 'No such key exists')

The method when invoked will thus return:

No such key exists

since there’s no ‘d’ key in the above dictionary.

Hello. After watching all the videos about iterating through dictionary, I couldn’t find one that shows how to iterate where ‘values’ are list with multiple strings in them… Like this kind of thing:

scene = { "objects": [], "camera": ['camera1'], "lights": ['light1', 'light2', 'light3']  }

I’m a beginner so I can’t really figure out how to go through all these “Keys” and then loop through all the “values” list and extract them.

Cheers,

Jacques.

@jacquesd One way to do that would involve using two nested for loops:

>>> scene = {
...     "objects": [],
...     "cameras": ["camera1"],
...     "lights": ["light1", "light2", "light3"]
... }
>>> 
>>> for component, values in scene.items():
...     print(component.upper())
...     for value in values:
...         print(" -", value)
... 
OBJECTS
CAMERAS
 - camera1
LIGHTS
 - light1
 - light2
 - light3

Thank you very much Bartosz! I knew the logic but couldn’t figure out how to implement it.

Cheers,

Jacques.

What is the difference between bad_guys.items() and list(bad_guys.items())? In the video, the insturctor says that .items() will return a list of key-value pairs. If that’s so, then why do we need to list the list to turn the key-value pairs into tuples?

@h-dzeba Bad guys are a Python dictionary:

>>> bad_guys = {
...     "daredevil": "kingpin",
...     "batman": "bane",
...     "deadpool": "evil dead pool"
... }

Calling .items() on them will return a list-like dict_items object comprised of key-value pairs:

>>> bad_guys.items()
dict_items([('daredevil', 'kingpin'), ('batman', 'bane'), ('deadpool', 'evil dea
d pool')])

Since this object is an iterable, there’s no difference whether you use it directly in a for-loop or convert it to a plain old list first:

>>> list(bad_guys.items())
[('daredevil', 'kingpin'), ('batman', 'bane'), ('deadpool', 'evil dead pool')]

When trying to apply the update built in function, i’m give a syntax error. d.update(3 = ‘nemico’,) SyntaxError: expression cannot contain assignment, perhaps you meant “==”? What am I doing wrong?