Add JNI for extract_list_element with index column (#10341)

This PR is to expose the `cudf::list::extract_list_element(column_view, column_view)` API to JNI, along with its tests. closes #10340 Signed-off-by: Firestarman <[email protected]> Authors: - Liangcai Li (https://github.com/firestarman) Approvers: - Robert (Bobby) Evans (https://github.com/revans2) URL: #10341
rapidsai · Feb 22, 2022 · add6990 · add6990
1 parent 58810af
commit add6990
Show file tree

Hide file tree

Showing 3 changed files with 53 additions and 11 deletions.
diff --git a/java/src/main/java/ai/rapids/cudf/ColumnView.java b/java/src/main/java/ai/rapids/cudf/ColumnView.java
@@ -2260,6 +2260,25 @@ public final ColumnVector extractListElement(int index) {
     return new ColumnVector(extractListElement(getNativeView(), index));
   }
 
+  /**
+   * For each list in this column pull out the entry at the corresponding index specified in
+   * the index column. If the entry goes off the end of the list a NULL is returned instead.
+   *
+   * The index column should have the same row count with the list column.
+   *
+   * @param indices a column of 0 based offsets into the list. Negative values go backwards from
+   *                the end of the list.
+   * @return a new column of the values at those indexes.
+   */
+  public final ColumnVector extractListElement(ColumnView indices) {
+    assert type.equals(DType.LIST) : "A column of type LIST is required for .extractListElement()";
+    assert indices != null && DType.INT32.equals(indices.type)
+        : "indices should be non-null and integer type";
+    assert indices.getRowCount() == rows
+        : "indices must have the same row count with list column";
+    return new ColumnVector(extractListElementV(getNativeView(), indices.getNativeView()));
+  }
+
   /**
    * Create a new LIST column by copying elements from the current LIST column ignoring duplicate,
    * producing a LIST column in which each list contain only unique elements.
@@ -3752,6 +3771,8 @@ private static native long stringReplaceWithBackrefs(long columnView, String pat
 
   private static native long extractListElement(long nativeView, int index);
 
+  private static native long extractListElementV(long nativeView, long indicesView);
+
   private static native long dropListDuplicates(long nativeView);
 
   private static native long dropListDuplicatesWithKeysValues(long nativeHandle);

diff --git a/java/src/main/native/src/ColumnViewJni.cpp b/java/src/main/native/src/ColumnViewJni.cpp
@@ -392,6 +392,21 @@ JNIEXPORT jlong JNICALL Java_ai_rapids_cudf_ColumnView_extractListElement(JNIEnv
   CATCH_STD(env, 0);
 }
 
+JNIEXPORT jlong JNICALL Java_ai_rapids_cudf_ColumnView_extractListElementV(JNIEnv *env, jclass,
+                                                                           jlong column_view,
+                                                                           jlong indices_view) {
+  JNI_NULL_CHECK(env, column_view, "column is null", 0);
+  JNI_NULL_CHECK(env, indices_view, "indices is null", 0);
+  try {
+    cudf::jni::auto_set_device(env);
+    cudf::column_view *indices = reinterpret_cast<cudf::column_view *>(indices_view);
+    cudf::column_view *cv = reinterpret_cast<cudf::column_view *>(column_view);
+    cudf::lists_column_view lcv(*cv);
+    return release_as_jlong(cudf::lists::extract_list_element(lcv, *indices));
+  }
+  CATCH_STD(env, 0);
+}
+
 JNIEXPORT jlong JNICALL Java_ai_rapids_cudf_ColumnView_dropListDuplicates(JNIEnv *env, jclass,
                                                                           jlong column_view) {
   JNI_NULL_CHECK(env, column_view, "column is null", 0);

diff --git a/java/src/test/java/ai/rapids/cudf/ColumnVectorTest.java b/java/src/test/java/ai/rapids/cudf/ColumnVectorTest.java
@@ -4360,17 +4360,23 @@ void testsubstring() {
 
   @Test
   void testExtractListElements() {
-      try (ColumnVector v = ColumnVector.fromStrings("Héllo there", "thésé", null, "", "ARé some", "test strings");
-           ColumnVector expected = ColumnVector.fromStrings("Héllo",
-                   "thésé",
-                   null,
-                   "",
-                   "ARé",
-                   "test");
-           ColumnVector tmp = v.stringSplitRecord(" ");
-           ColumnVector result = tmp.extractListElement(0)) {
-          assertColumnsAreEqual(expected, result);
-      }
+    try (ColumnVector v = ColumnVector.fromStrings("Héllo there", "thésé", null, "", "ARé some", "test strings");
+         ColumnVector expected = ColumnVector.fromStrings("Héllo", "thésé", null, "", "ARé", "test");
+         ColumnVector list = v.stringSplitRecord(" ");
+         ColumnVector result = list.extractListElement(0)) {
+      assertColumnsAreEqual(expected, result);
+    }
+  }
+
+  @Test
+  void testExtractListElementsV() {
+    try (ColumnVector v = ColumnVector.fromStrings("Héllo there", "thésé", null, "", "ARé some", "test strings");
+         ColumnVector indices = ColumnVector.fromInts(0, 2, 0, 0, 1, -1);
+         ColumnVector expected = ColumnVector.fromStrings("Héllo", null, null, "", "some", "strings");
+         ColumnVector list = v.stringSplitRecord(" ");
+         ColumnVector result = list.extractListElement(indices)) {
+      assertColumnsAreEqual(expected, result);
+    }
   }
 
   @Test