Using json data to change colour

Processing.py
1

Hello,

I am trying to create a sketch that uses from a json file to r value to change colour. In the terminal, it shows the value changing, but the colour are not changing. Here is code:

import json

def setup():
    size(720,480)
    global jsondata, heart
    jsondata = open('heart_rate-2020-09-11.json')
    heart = json.load(jsondata)
    
def draw():
    for beat in heart:
        bpm = beat['value']['bpm']
        print(bpm)
        fill(bpm, 0, 0)
        circle(width/2, height/2, 200)
2

I realise why it was not changing. It was making a circle for each value and putting them all on top of each other. How do I enable it to read through each value one at a time?

1 Like
3

Welcome, @fleshcircuit

Yes – every circle is drawn over the last one. You only see the final circle drawn on each frame.

You want to draw one circle per frame; you’re drawing several each frame. I don’t know what your JSON data looks like, so I’ve created some placeholder dictionary values. I’m using a modulo operation with the frameCount to pick row values:

def setup():
    frameRate(3) # slow down frame rate to see what's happening
    
    size(720,480)
    global jsondata, heart
    heart = [
      {'value': {'bpm': 0}},
      {'value': {'bpm': 100}},
      {'value': {'bpm': 200}},
    ]
    
def draw():
    background(255, 255, 255)  # clear previous frame
    heart_total = len(heart)  # total entries in heart data
    heart_row = frameCount % heart_total  # pick a row
    
    bpm = heart[heart_row]['value']['bpm']
    print(bpm)
    fill(bpm, 0, 0)
    circle(width/2, height/2, 200)

The heart_row is equal to 1 on the first frame, 2 on the second. Then it ‘wraps back around’ to 0 again for the third frame, and so on.

3 Likes
4

Thank you! I will try it out.