FAQ

This documentation describes Heartex platform version 1.0.0, which is no longer supported. For information about troubleshooting or predictions in Label Studio Enterprise Edition, the equivalent of Heartex platform version 2.0.x, see Troubleshoot Label Studio and Import pre-annotations into Label Studio.

Frequently asked questions about setup and usage.

Image/audio/resource loading error while labeling

The most common mistake while resource loading is CORS (Cross-Origin Resource Sharing) problem or Cross Domain. When you are trying to fetch a picture from external hosting it could be blocked by security reasons. Go to browser console (Ctrl + Shift + i for Chrome) and check errors there. Typically, this problem is solved by the external host setup.

• If you have an access to the hosting server as admin then you need to allow CORS for the web server. For nginx you can try to add these lines to /etc/nginx/nginx.conf into your location section:

  location <YOUR_LOCATION> {
       if ($request_method = 'OPTIONS') {
          add_header 'Access-Control-Allow-Origin' '*';
          add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
          #
          # Custom headers and headers various browsers *should* be OK with but aren't
          #
          add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
          #
          # Tell client that this pre-flight info is valid for 20 days
          #
          add_header 'Access-Control-Max-Age' 1728000;
          add_header 'Content-Type' 'text/plain; charset=utf-8';
          add_header 'Content-Length' 0;
          return 204;
       }
       if ($request_method = 'POST') {
          add_header 'Access-Control-Allow-Origin' '*';
          add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
          add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
          add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';
       }
       if ($request_method = 'GET') {
          add_header 'Access-Control-Allow-Origin' '*';
          add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
          add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
          add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';
       }
  }

• If you use Amazon S3 with LS read this manual.

• Not every host supports CORS setup, but you may to try find these settings in the admin area.

How to make pre-annotations & pre-labeling

You can import pre-annotated tasks into LS. Pre-annotations will be automatically shown on Labeling page. Prepare your tasks with predictions field which is very similar to completions and then import your tasks to LS. Read more about task format and predictions.

[{
  "data": {
    "my_text": "This is great" 
  },

  "predictions": [{
    "result": [{
      "from_name": "sentiment_class",
      "to_name": "message",
      "type": "choices",
      "value": {
        "choices": ["Positive"]
      }
    }]
  }]
}]

How to write your own machine learning backend

Read this page to start writing your own ML backend.