How to print specific data from JSON file lists in a line break layout?

April 7, 2022

Take this example:

    "something": {
        "random": 0,
        "bag": {
            "papers": 0,
            "pencils": 0
        },
        "PAINT": {
            "COLORS": [
                "A WHITE",
                "B MAPLE",
                "B LOTUS",
                "A OLIVE"
            ],
            "CANS": [
                "SOMETHING"
            ] 
    }

Ignore everything and focus on the COLORS list in the PAINT dictionary… I want to print all colors that have the color A before them, as a code. In other words I want to print "A WHITE" and "A OLIVE". Here’s what happens when I do this:

with open("somethings.json", "r") as f:
   data = json.load(f)

print(data["something"]["PAINT"]["COLORS"])

This is the output:

["A WHITE", "B MAPLE", "B LOTUS", "A OLIVE"]

but like I said, I do not want that… I want only A colors to be printed…
I also do not want THIS:

["A WHITE", "A OLIVE"]

the output that I really want (which is quite specific) is this:

OLIVE
WHITE

With line breaks (optional: AND in alphabetical order) that is the output that I want. So how can I print this output? is it possible without using any ‘for’ loops? This is a very specific question, would appreciate some help. Thanks –

>Solution :

Try this code:

with open("somethings.json", "r") as f:
   data = json.load(f)

a_colors = [color for color in data["something"]["PAINT"]["COLORS"] if color.startswith("A ")]
colors = [a_color.replace("A ", "") for a_color in a_colors]

print(colors)

How it works

Opens and loads the JSON data.
Uses a list comprehension to filter only entries that start with "A ".
The .startswith() method of a string returns a boolean value, True if the first few characters of the string are, in fact, the characters passed as an argument, and False otherwise.
Uses another list comprehension to get the string without the "A " for each string in the list created in step 2.
Replaces the "A " with an empty string, which is a hacky way of deleting part of a string using the .replace() method.

It can be done without list comprehensions using a for loop as well

See code below:

with open("somethings.json", "r") as f:
   data = json.load(f)

a_colors = []
for color in data["something"]["PAINT"]["COLORS"]:
    if color.startswith("A "):
        color_without_a = color.replace("A ", "")
        a_colors.append(color_without_a)

print(a_colors)

This solution uses a for loop rather than a list comprehension but is otherwise the same. (If you are confused, see below for a solution which is an exact replica of the list comprehension one but implemented with for loops).

If you are interested, here is a lengthier solution more similar to the list comprehension one, using for loops:

with open("somethings.json", "r") as f:
   data = json.load(f)

a_colors = []

for color in data["something"]["PAINT"]["COLORS"]:
    if color.startswith("A "):
        a_colors.append(color)

colors = []

for a_color in a_colors:
    colors.append(a_color.replace("A ", ""))
    
print(a_colors)