ENH: Add Array2D(numberOfRows, numberOfCols, initialValue) constructor

Allows constructing an `Array2D` with each element having the specified initial
value.

Modules/Core/Common/include/itkArray2D.h

@@ -53,6 +53,10 @@ class ITK_TEMPLATE_EXPORT Array2D : public vnl_matrix<TValue>
   /** Constructs a matrix of the specified number of rows and columns. */
   Array2D(unsigned int numberOfRows, unsigned int numberOfCols);
 
+  /** Constructs a matrix of the specified number of rows and columns, with each element having the specified initial
+   * value. */
+  Array2D(unsigned int numberOfRows, unsigned int numberOfCols, const TValue & initialValue);
+
   /** Copy-constructor. */
   Array2D(const Self & array);
 

Modules/Core/Common/include/itkArray2D.hxx

@@ -27,6 +27,11 @@ Array2D<TValue>::Array2D(unsigned int numberOfRows, unsigned int numberOfCols)
   : vnl_matrix<TValue>(numberOfRows, numberOfCols)
 {}
 
+template <typename TValue>
+Array2D<TValue>::Array2D(unsigned int numberOfRows, unsigned int numberOfCols, const TValue & initialValue)
+  : vnl_matrix<TValue>(numberOfRows, numberOfCols, initialValue)
+{}
+
 template <typename TValue>
 Array2D<TValue>::Array2D(const VnlMatrixType & matrix)
   : vnl_matrix<TValue>(matrix)

Modules/Core/Common/test/CMakeLists.txt

@@ -1712,6 +1712,7 @@ if(ITK_BUILD_SHARED_LIBS AND ITK_DYNAMIC_LOADING)
 endif()
 
 set(ITKCommonGTests
+    itkArray2DGTest.cxx
     itkAggregateTypesGTest.cxx
     itkBitCastGTest.cxx
     itkBooleanStdVectorGTest.cxx

Modules/Core/Common/test/itkArray2DGTest.cxx

@@ -0,0 +1,53 @@
+/*=========================================================================
+ *
+ *  Copyright NumFOCUS
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *         https://www.apache.org/licenses/LICENSE-2.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *=========================================================================*/
+
+// First include the header file to be tested:
+#include "itkArray2D.h"
+#include <gtest/gtest.h>
+#include <limits>
+
+
+// Tests that Array2D may be constructed with an initial value for each element.
+TEST(Array2D, ConstructorSupportsInitialValue)
+{
+  const auto checkConstructor =
+    [](const unsigned int numberOfRows, const unsigned int numberOfCols, const auto initialValue) {
+      using ValueType = std::remove_const_t<decltype(initialValue)>;
+
+      const itk::Array2D<ValueType> array2D(numberOfRows, numberOfCols, initialValue);
+
+      EXPECT_EQ(array2D.rows(), numberOfRows);
+      EXPECT_EQ(array2D.columns(), numberOfCols);
+
+      for (const auto & element : array2D)
+      {
+        EXPECT_EQ(element, initialValue);
+      }
+    };
+
+  for (const auto initialValue : { -1, 0, 1 })
+  {
+    checkConstructor(0, 0, initialValue);
+    checkConstructor(1, 2, initialValue);
+  }
+  for (const auto initialValue : { std::numeric_limits<double>::min(), std::numeric_limits<double>::max() })
+  {
+    checkConstructor(0, 0, initialValue);
+    checkConstructor(1, 2, initialValue);
+  }
+}