What are the rules for class names in IBM Watson Visual Recognition service?

Question

I'm exploring IBM Watson Visual Recognition service and when I create a classifier using classnames like 'black-dog' (i.e. black-dog_positive_example), this classname is later returned as 'black_dog' (with underscore replacing dash) when I classify an image using the /v3/classify endpoint.

But when I retrieve the classifier details with the /v3/classifiers/{classifier_id} the class is correctly listed as 'black-dog'.

So, my result for GET /v3/classifiers/{classifier_id} is like:

{
    "classifier_id": "dog_561932172",
    "name": "dog",
    "owner": "xxxxxxxx-xxx-xxx-xxx-xxxxxxxxxxxx",
    "status": "ready",
    "created": "2016-07-30T22:06:39.327Z",
    "classes": [
        {"class": "black-dog"}
    ]
}

While my result for GET /v3/classify is

{
  "custom_classes": 1,
  "images": [
    {
      "classifiers": [
        {
          "classes": [
            {
              "class": "black_dog",
              "score": 0.546941
            }
          ],
          "classifier_id": "dog_561932172",
          "name": "dog"
        }
      ],
      "image": "20160620_142113.jpg"
    }
  ],
  "images_processed": 1
}

So is this expected or a defect? Should I avoid using "-" in class names? Are there any other rules for the value of a classname?

Looks like a defect to me, so thanks for bringing this up. A good way to avoid this would to not use dashes. However, let me get in contact with the Visual Recognition team to verify whether or not this is expected behavior. I looked in the API reference and couldn't find any rules regarding the classname. — joe

Matt Hill Matt Hill · Accepted Answer · 2016-09-06T23:14:36

Are there any other rules for the value of a classname?

We made an update, and the service should no longer modify any class names like replacing a dash with an underscore. Instead, it will not accept class names with any of these characters for custom learning: \,|,*,{,},$,-,/,',`,"

(You'll see the dash is included in there.) Spaces are acceptable. The update is not retroactive, so existing class names that were modified during training are not affected.

What are the rules for class names in IBM Watson Visual Recognition service?

2 Answers