OpenAI: embeddings

app/src/main/java/eu/faircode/email/OpenAI.java

@@ -109,6 +109,20 @@ public class OpenAI {
         }
     }
 
+    static double[] getEmbedding(Context context, String text, String model) throws JSONException, IOException {
+        // https://platform.openai.com/docs/api-reference/embeddings
+        JSONObject jrequest = new JSONObject();
+        jrequest.put("input", text);
+        jrequest.put("model", model == null ? "text-embedding-ada-002" : model);
+        JSONObject jresponse = call(context, "POST", "v1/embeddings", jrequest);
+        JSONObject jdata = jresponse.getJSONArray("data").getJSONObject(0);
+        JSONArray jembedding = jdata.getJSONArray("embedding");
+        double[] result = new double[jembedding.length()];
+        for (int i = 0; i < jembedding.length(); i++)
+            result[i] = jembedding.getDouble(i);
+        return result;
+    }
+
     static Message[] completeChat(Context context, String model, Message[] messages, Float temperature, int n) throws JSONException, IOException {
         // https://platform.openai.com/docs/guides/chat/introduction
         // https://platform.openai.com/docs/api-reference/chat/create
@@ -238,4 +252,26 @@ public class OpenAI {
             return this.role + ": " + this.content;
         }
     }
+
+    static class Embedding {
+        public static double getSimilarity(double[] v1, double[] v2) {
+            if (v1.length != v2.length)
+                throw new IllegalArgumentException("Invalid vector length=" + v1.length + "/" + v2.length);
+            double dotProduct = dotProduct(v1, v2);
+            double magV1 = magnitude(v1);
+            double magV2 = magnitude(v2);
+            return dotProduct / (magV1 * magV2);
+        }
+
+        private static double dotProduct(double[] v1, double[] v2) {
+            float val = 0;
+            for (int i = 0; i <= v1.length - 1; i++)
+                val += v1[i] * v2[i];
+            return val;
+        }
+
+        private static double magnitude(double[] v) {
+            return Math.sqrt(dotProduct(v, v));
+        }
+    }
 }