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03-3-python-json-files.md

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Data 3-3: Python - JSON

Writing a JSON file

import json

rows = [
    {"name": "Rachel", "age": 34},
    {"name": "Monica", "age": 34},
    {"name": "Phoebe", "age": 37}
]

with open('testwrite.json', 'w') as f:
    json.dump(rows, f)

Opening a JSON file

This snippet reads test.json and loads the contents as a dict into the variable data.

import json

with open('friends.json', 'r') as f:
    data = json.load(f)
    
print(data)

➡️ Try It

In a new file called cookveggies.py

  1. Read output/vegetables.csv (see previous section) into a variable called vegetables.

  2. Print the variable vegetables.

  3. Write vegetables as a JSON file called output/vegetables.json. It should look like this:

    [
  { "name": "eggplant", "color": "purple" },
  { "name": "tomato", "color": "red" },
  { "name": "corn", "color": "yellow" },
  { "name": "okra", "color": "green" },
  { "name": "arugula", "color": "green" },
  { "name": "broccoli", "color": "green" }
]

❇️ Example

Download superheroes.json

wget https://mdn.github.io/learning-area/javascript/oojs/json/superheroes.json

then write a python program that

  1. Reads superheroes.json (in this folder)
  2. Creates an empty array called powers
  3. Loop thorough the members of the squad, and append the powers of each to the powers array.
  4. Prints those powers to the terminal

Bonus: make the list of powers unique and print it again

hint for bonus: To get the unique elements in a list use the set method. For example, try running list(set([1, 1, 2, 3])) in your python console. Alternatively you can use an if statement to only add the powers to the list if they are not already in there.

➡️ Try It

Lets Read superheroes.json (in this folder) and output a flat CSV of members. The columns should be: name, age, secretIdentity, powers, squadName, homeTown, formed, secretBase, active. Any column that is top level, such as squadName should just be repeated for every row.

Here is an example set of steps:

  1. Read superheroes.json
  2. Write a header to the CSV file
  3. Loop over the members, and for each member write a row to the csv file

The output should look like this:

name age secretIdentity powers squadName homeTown formed secretBase active
Molecule Man 29 Dan Jukes ['Radiation resistance', 'Turning tiny', 'Radiation blast'] Super hero squad Metro City 2,016 Super tower True
Madame Uppercut 39 Jane Wilson ['Million tonne punch', 'Damage resistance', 'Superhuman reflexes'] Super hero squad Metro City 2,016 Super tower True
Eternal Flame 1,000,000 Unknown ['Immortality', 'Heat Immunity', 'Inferno', 'Teleportation', 'Interdimensional travel'] Super hero squad Metro City 2,016 Super tower True

Bonus

Write one row per power rather than one row per member.