Week 3: Session 2

Internet API Read

Activity 1: Review Week 3 Session 1

• Computer I/O

• Reading and Writing files

Activity 2: Demostrate where JSON is used in the Game.

Activity 3: Introduction to JSON data format

The data format most used on the internet is called JSON (pronounced JASON). It's an acronym for JavaScript Object Notation. JSON looks kind of like a dictionary structure. It is more strict and requires all strings use double quotes.

An API is an "Application Programming Interface". It looks like a website and sometimes it can be pasted in the browser to pull back data like a web page. We'll be working with the Numbers API.

Excecise

Copy and Paste this URL into a browser and see what you get back: http://numbersapi.com/19

Try changing the number from 19 to some other number. What does this API do?

Copy and Paste this URL into a browser and see what you get back: http://numbersapi.com/19?json

We added "?json" and what changed? We'll add the ?json when we make a request to numbers api from python code.

Activity 4: Transform a Dictionary into a valid JSON string using dumps

Is there a difference between the Dictionary and the JSON?

import json
print(json.dumps({'name': 'Maria', 'age': 20, 'occupation': 'programmer'}))

What happens if you try to use dumps with invalid JSON

In Python None means nothing but it is not recognized by the Python dumps command. In JSON, the concept is nothing is specified by null. What does the following code do?

import json
print(json.dumps({'name': 'Maria', 'age': 20, 'occupation': None}))

Activity 5: Transform a String into JSON using load as we read in a file

What do you see when you run this? What happens if you change "programmer" to null?

import json
str = '{"name": "Maria", "age": 20, "occupation": "programmer"}'
j = json.loads(str)
print (j)

Activity 6: Write JSON to a local File

import json
myfile = open("local.json","w")
myfile.write(json.dumps({'name': 'Maria', 'age': 20, 'occupation': 'programmer'}))
myfile.close()
print (myfile.name, "is open?", myfile.closed)

Activity 7: Read JSON from a local File

This is another way to open a file and make variable out of the filename.

import json

with open('local.json', 'r') as f:
    dict = json.load(f)
print(dict)

Activity 8: Read JSON from the Internet

We've got all the skills to read from the internet now. We can get data from the numbers api and examine the various types using the type function.

import requests, json

data = requests.get("http://numbersapi.com/19?json")
dict = json.loads(data.content)
print(dict)

print ("The type of the object  returned from the internet is", type(data))
print ("The type of the content returned from the internet is", type(data.content))
print ("The type of the data that the json.loads command creates is ", type(dict))

print("The interesting thing about 19 is: ", dict["text"])

Excercise:

Create a challenge where you ask the user to guess a number. If they guess correctly call the numbers API and report back what is interesting about that number.