Add predictProbaWithThreshold method

README.md

@@ -4,7 +4,7 @@ fastText-jni is a Java wrapper for [fastText](https://github.com/facebookresearc
 
 ## Usage
 
-`implementation group: 'com.diffbot', name: 'fasttext-jni', version: '0.9.2.7'`
+`implementation group: 'com.diffbot', name: 'fasttext-jni', version: '0.9.2.8'`
 
 ```java
 FastTextModel model;

build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 group = 'com.diffbot'
-version = '0.9.2.7'
+version = '0.9.2.8'
 
 sourceCompatibility = 11
 targetCompatibility = 11

src/main/java/com/diffbot/fasttext/FastTextModel.java

@@ -27,6 +27,7 @@ public FastTextModel(InputStream inputStream) throws IOException {
     private native void load(ByteBuffer byteBuffer);
     public native Prediction predictProba(String s);
     public native Prediction[] predictProbaTopK(String s, int k);
+    public native Prediction[] predictProbaWithThreshold(String s, float threshold);
 
     @Override
     public native void close();

src/main/native/fasttext_jni.cc

@@ -102,9 +102,7 @@ JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictPr
         return NULL;
     }
 
-    if (predictions.size() < k) {
-        k = predictions.size();
-    }
+    k = predictions.size();
     jobjectArray top_k_predictions = env->NewObjectArray(k, predictionClass, nullptr);
 
     for (int i = 0; i < k; i++) {
@@ -118,6 +116,36 @@ JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictPr
     return top_k_predictions;
 }
 
+JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictProbaWithThreshold
+(JNIEnv *env, jobject obj, jstring s, jfloat threshold) {
+
+    jboolean isCopy;
+    const char* utf_string = env->GetStringUTFChars(s, &isCopy);
+    FastTextWrapper *ft = (FastTextWrapper *) env->GetLongField(obj, handleFieldID);
+    std::vector<std::pair<fasttext::real,std::string>> predictions;
+    std::string text = utf_string;
+    std::stringstream stream;
+    stream << text << '\n';
+    bool result = ft->predictLine(stream, predictions, -1, threshold);
+    env->ReleaseStringUTFChars(s, utf_string);
+    if (!result || predictions.size() == 0) {
+        return NULL;
+    }
+
+    jsize k = predictions.size();
+    jobjectArray ret = env->NewObjectArray(k, predictionClass, nullptr);
+
+    for (int i = 0; i < k; i++) {
+        std::pair<fasttext::real, std::string> prediction = predictions[i];
+
+        jstring label = env->NewStringUTF(prediction.second.c_str());
+        jobject pred = env->NewObject(predictionClass, predictionConstructor, prediction.first, label);
+        env->SetObjectArrayElement(ret, i, pred);
+    }
+
+    return ret;
+}
+
 JNIEXPORT void JNICALL Java_com_diffbot_fasttext_FastTextModel_close
 (JNIEnv *env, jobject obj) {
     FastTextWrapper *ft = (FastTextWrapper *) env->GetLongField(obj, handleFieldID);

src/main/native/fasttext_jni.h

@@ -23,13 +23,21 @@ JNIEXPORT void JNICALL Java_com_diffbot_fasttext_FastTextModel_load
 JNIEXPORT jobject JNICALL Java_com_diffbot_fasttext_FastTextModel_predictProba
   (JNIEnv *, jobject, jstring);
 
-  /*
-   * Class:     com_diffbot_fasttext_FastTextModel
-   * Method:    predictProbaTopK
-   * Signature: (Ljava/lang/String;I)[Lcom/diffbot/fasttext/Prediction;
-   */
-  JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictProbaTopK
-    (JNIEnv *, jobject, jstring, jint);
+/*
+ * Class:     com_diffbot_fasttext_FastTextModel
+ * Method:    predictProbaTopK
+ * Signature: (Ljava/lang/String;I)[Lcom/diffbot/fasttext/Prediction;
+ */
+JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictProbaTopK
+  (JNIEnv *, jobject, jstring, jint);
+
+/*
+ * Class:     com_diffbot_fasttext_FastTextModel
+ * Method:    predictProbaWithThreshold
+ * Signature: (Ljava/lang/String;F)[Lcom/diffbot/fasttext/Prediction;
+ */
+JNIEXPORT jobjectArray JNICALL Java_com_diffbot_fasttext_FastTextModel_predictProbaWithThreshold
+  (JNIEnv *, jobject, jstring, jfloat);
 
 /*
  * Class:     com_diffbot_fasttext_FastTextModel

src/test/java/com/diffbot/fasttext/FastTextTest.java

@@ -11,7 +11,6 @@ public class FastTextTest {
 
     @Test
     public void modelTest() throws IOException {
-        Prediction prediction;
         FastTextModel model;
         /*
          * language identification
@@ -21,16 +20,34 @@ public void modelTest() throws IOException {
             model = new FastTextModel(inputStream);
         }
 
-        prediction = model.predictProba("Web Data for your AI Imagine if your app could access the web like a structured database .");
-        System.out.println(prediction.label + " : " + prediction.probability);
-        Assertions.assertEquals("__label__en", prediction.label);
+        {
+            Prediction prediction = model.predictProba("Web Data for your AI Imagine if your app could access the web like a structured database .");
+            System.out.println(prediction.label + " : " + prediction.probability);
+            Assertions.assertEquals("__label__en", prediction.label);
+        }
 
-        prediction = model.predictProba("AI のための Web データ アプリが構造化データベースのように Web にアクセスできるかどうかを想像してください。");
-        System.out.println(prediction.label + " : " + prediction.probability);
-        Assertions.assertEquals("__label__ja", prediction.label);
+        {
+            Prediction prediction = model.predictProba("AI のための Web データ アプリが構造化データベースのように Web にアクセスできるかどうかを想像してください。");
+            System.out.println(prediction.label + " : " + prediction.probability);
+            Assertions.assertEquals("__label__ja", prediction.label);
+        }
 
-        Prediction[] predictions = model.predictProbaTopK(" ", -1);
-        Assertions.assertEquals(predictions.length, 176);
+        {
+            Prediction[] predictions = model.predictProbaTopK(" ", -1);
+            Assertions.assertEquals(176, predictions.length);
+        }
+
+        {
+            float threshold = 0.01f;
+            Prediction[] predictions = model.predictProbaWithThreshold(" ", threshold);
+            Assertions.assertEquals(24, predictions.length);
+            double prev = Float.MAX_VALUE;
+            for (Prediction prediction : predictions) {
+                Assertions.assertTrue(prediction.probability >= threshold);
+                Assertions.assertTrue(prediction.probability <= prev);
+                prev = prediction.probability;
+            }
+        }
 
         model.close();
 
@@ -42,7 +59,7 @@ public void modelTest() throws IOException {
             model = new FastTextModel(inputStream);
         }
 
-        prediction = model.predictProba("web data for your ai imagine if your app could access the web like a structured database .");
+        Prediction prediction = model.predictProba("web data for your ai imagine if your app could access the web like a structured database .");
         System.out.println(prediction.label + " : " + prediction.probability);
         Assertions.assertEquals("__label__4", prediction.label);
 
@@ -54,7 +71,7 @@ public void modelTest() throws IOException {
             System.out.println(p.label + " : " + p.probability);
         }
 
-        Assertions.assertEquals(array.length, 4);
+        Assertions.assertEquals(4, array.length);
 
         model.close();
     }