remove unknown

src/main/scala/com/aliyun/odps/spark/examples/myUtils/FeatureTransformV2.java

@@ -303,7 +303,7 @@ public class FeatureTransformV2 {
         for (String attr : videoCateAttrs) {
             String attrVal = videoInfo.getOrDefault(attr, "");
             attrVal = attrVal.trim();
-            if (!attrVal.isEmpty()) {
+            if (!attrVal.isEmpty() && !attrVal.equals("unknown")) {
                 String key = String.format("%s@%s@%s", prefix, attr, attrVal);
                 featMap.put(key, 1.0);
             }