How to draw/visualize data from JSON file?

sc0rpqu33n

Hi, so I have successfully imported my JSON file into processing, but now I am trying to draw plot point or lines that represent the longitude and latitude. I have tried searching on here for solutions, but I am just more confused now. I will paste my current code below...

JSONObject json, iss_position;
String message;
int timestamp;
float latitude, longitude;

void setup() {
  size(500, 500);
  noStroke();
}

void draw() {
  background(0);
  json = loadJSONObject("http://api.open-notify.org/iss-now.json");
  iss_position = json.getJSONObject("iss_position");
  message = json.getString("message");
  timestamp = json.getInt("timestamp");
  latitude = iss_position.getFloat("latitude");
  longitude = iss_position.getFloat("longitude");

  println(message + ", " + timestamp + ", " + latitude + ", " + longitude);

  ellipse(latitude, longitude, 10, 10);
  text("TIME: "+timestamp, 10,450);
  text("LATITUDE: "+latitude, 10,470);
  text("LONGITUDE "+longitude, 10,490);

}

koogs

Edit post, highlight code, press ctrl-o to format

Don't load files within draw, draw is called 60 times a second and loading a file is too expensive to be called that often. It'll also annoying the website.

koogs

{
  "timestamp": 1507362311, 
  "message": "success", 
  "iss_position": {
    "longitude": "166.2819", 
    "latitude": "51.2426"
  }
}

Note also that latitude and longitude are within another element called iss_position

Edit: ok, you've seen that. What does the output say, do you see sensible looking values?

koogs

yeah, have run that now and the json parsing looks fine. the problem is the domain and range - you need to map the numbers you get so that they are sensible screen coordinates.

i just got

success, 1507366342, -2.4234, 47.8786

which is slightly off the screen in the x direction, 47 pixels down from the top. it also suggests that the x can be negative. in fact latitude (y) can go from -90 (south pole) to +90 (north pole) and longitude (x) can be from 0 to 360 (or possibly from -180 to 180).

look at map() in the reference.