Support column major array. (#6765)

tests/cpp/data/test_adapter.cc

@@ -138,5 +138,4 @@ TEST(Adapter, IteratorAdapter) {
   }
   ASSERT_EQ(num_batch, 1);
 }
-
 }  // namespace xgboost

tests/cpp/data/test_array_interface.cc

@@ -38,17 +38,28 @@ TEST(ArrayInterface, Error) {
         Json(Boolean(false))};
 
   auto const& column_obj = get<Object>(column);
+  std::pair<size_t, size_t> shape{kRows, kCols};
+  std::string typestr{"<f4"};
+
   // missing version
-  EXPECT_THROW(ArrayInterfaceHandler::ExtractData<float>(column_obj), dmlc::Error);
+  EXPECT_THROW(ArrayInterfaceHandler::ExtractData(column_obj,
+                                                  StringView{typestr}, shape),
+               dmlc::Error);
   column["version"] = Integer(static_cast<Integer::Int>(1));
   // missing data
-  EXPECT_THROW(ArrayInterfaceHandler::ExtractData<float>(column_obj), dmlc::Error);
+  EXPECT_THROW(ArrayInterfaceHandler::ExtractData(column_obj,
+                                                  StringView{typestr}, shape),
+               dmlc::Error);
   column["data"] = j_data;
   // missing typestr
-  EXPECT_THROW(ArrayInterfaceHandler::ExtractData<float>(column_obj), dmlc::Error);
+  EXPECT_THROW(ArrayInterfaceHandler::ExtractData(column_obj,
+                                                  StringView{typestr}, shape),
+               dmlc::Error);
   column["typestr"] = String("<f4");
   // nullptr is not valid
-  EXPECT_THROW(ArrayInterfaceHandler::ExtractData<float>(column_obj), dmlc::Error);
+  EXPECT_THROW(ArrayInterfaceHandler::ExtractData(column_obj,
+                                                  StringView{typestr}, shape),
+               dmlc::Error);
 
   HostDeviceVector<float> storage;
   auto array = RandomDataGenerator{kRows, kCols, 0}.GenerateArrayInterface(&storage);
@@ -56,7 +67,23 @@ TEST(ArrayInterface, Error) {
       Json(Integer(reinterpret_cast<Integer::Int>(storage.ConstHostPointer()))),
       Json(Boolean(false))};
   column["data"] = j_data;
-  EXPECT_NO_THROW(ArrayInterfaceHandler::ExtractData<float>(column_obj));
+  EXPECT_NO_THROW(ArrayInterfaceHandler::ExtractData(
+      column_obj, StringView{typestr}, shape));
 }
 
+TEST(ArrayInterface, GetElement) {
+  size_t kRows = 4, kCols = 2;
+  HostDeviceVector<float> storage;
+  auto intefrace_str = RandomDataGenerator{kRows, kCols, 0}.GenerateArrayInterface(&storage);
+  ArrayInterface array_interface{intefrace_str};
+
+  auto const& h_storage = storage.ConstHostVector();
+  for (size_t i = 0; i < kRows; ++i) {
+    for (size_t j = 0; j < kCols; ++j) {
+      float v0 = array_interface.GetElement(i, j);
+      float v1 = h_storage.at(i * kCols + j);
+      ASSERT_EQ(v0, v1);
+    }
+  }
+}
 }  // namespace xgboost

tests/python-gpu/test_gpu_prediction.py

@@ -210,9 +210,13 @@ class TestGPUPredict:
         cp.testing.assert_allclose(predt_from_array, predt_from_dmatrix)
 
         def predict_df(x):
-            inplace_predt = booster.inplace_predict(x)
+            # column major array
+            inplace_predt = booster.inplace_predict(x.values)
             d = xgb.DMatrix(x)
             copied_predt = cp.array(booster.predict(d))
+            assert cp.all(copied_predt == inplace_predt)
+
+            inplace_predt = booster.inplace_predict(x)
             return cp.all(copied_predt == inplace_predt)
 
         for i in range(10):

tests/python/test_predict.py

@@ -2,7 +2,10 @@
 from concurrent.futures import ThreadPoolExecutor
 import numpy as np
 from scipy import sparse
+import pytest
+import pandas as pd
 
+import testing as tm
 import xgboost as xgb
 
 
@@ -147,6 +150,19 @@ class TestInplacePredict:
         for i in range(10):
             run_threaded_predict(X, self.rows, predict_csr)
 
+    @pytest.mark.skipif(**tm.no_pandas())
+    def test_predict_pd(self):
+        X = self.X
+        # construct it in column major style
+        df = pd.DataFrame({str(i): X[:, i] for i in range(X.shape[1])})
+        booster = self.booster
+        df_predt = booster.inplace_predict(df)
+        arr_predt = booster.inplace_predict(X)
+        dmat_predt = booster.predict(xgb.DMatrix(X))
+
+        np.testing.assert_allclose(dmat_predt, arr_predt)
+        np.testing.assert_allclose(df_predt, arr_predt)
+
     def test_base_margin(self):
         booster = self.booster