From 31f23565ee923aa60501cbb6b4bb821ebd20d082 Mon Sep 17 00:00:00 2001
From: Oceania2018 <haiping008@gmail.com>
Date: Mon, 20 Jan 2020 16:28:51 -0600
Subject: [PATCH 1/3] mask setter

---
 src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs b/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
index d0b4f9ae..3b7f3eff 100644
--- a/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
+++ b/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
@@ -23,7 +23,11 @@ public NDArray this[NDArray<bool> mask]
             get => FetchIndices(this, np.nonzero(mask), null, true);
             set
             {
-                throw new NotImplementedException("Setter is not implemented yet");
+                for (int i = 0; i < mask.size; i++)
+                {
+                    if (mask.GetBoolean(i))
+                        this[i] = value;
+                }
             }
         }
     }

From e1b9e27301677558bdbe0508ac8890ed0c82f015 Mon Sep 17 00:00:00 2001
From: Oceania2018 <haiping008@gmail.com>
Date: Mon, 20 Jan 2020 17:00:28 -0600
Subject: [PATCH 2/3] add MaskSetter2D test

---
 .../NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs b/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
index 0bf41579..344684a8 100644
--- a/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
+++ b/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
@@ -74,6 +74,15 @@ public void MaskSetter()
             nd.Should().BeOfValues(-2, 2, -2, 4, -2, 6);
         }
 
+        [TestMethod]
+        public void MaskSetter2D()
+        {
+            var nd = np.arange(15).reshape(5, 3);
+            var mask = new NDArray(new bool[] { true, false, true, false, true }).MakeGeneric<bool>();
+            nd[mask] = 99;
+            nd.Should().BeOfValues(99, 99, 99, 3, 4, 5, 99, 99, 99, 9, 10, 11, 99, 99, 99);
+        }
+
         [TestMethod]
         public void Compare()
         {

From 04964ef284e2238b1a02d8ffa2eebb55fab311b2 Mon Sep 17 00:00:00 2001
From: Oceania2018 <haiping008@gmail.com>
Date: Mon, 20 Jan 2020 17:09:32 -0600
Subject: [PATCH 3/3] only work for 1d mask.

---
 .../Selection/NDArray.Indexing.Masking.cs           | 13 ++++++++++---
 .../Selection/NDArray.Indexing.Test.cs              |  9 +++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs b/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
index 3b7f3eff..c62eddfc 100644
--- a/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
+++ b/src/NumSharp.Core/Selection/NDArray.Indexing.Masking.cs
@@ -23,10 +23,17 @@ public NDArray this[NDArray<bool> mask]
             get => FetchIndices(this, np.nonzero(mask), null, true);
             set
             {
-                for (int i = 0; i < mask.size; i++)
+                if(mask.ndim == 1)
                 {
-                    if (mask.GetBoolean(i))
-                        this[i] = value;
+                    for (int i = 0; i < mask.size; i++)
+                    {
+                        if (mask.GetBoolean(i))
+                            this[i] = value;
+                    }
+                }
+                else
+                {
+                    throw new NotImplementedException("Setter is not implemented yet");
                 }
             }
         }
diff --git a/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs b/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
index 344684a8..de6a6615 100644
--- a/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
+++ b/test/NumSharp.UnitTest/Selection/NDArray.Indexing.Test.cs
@@ -83,6 +83,15 @@ public void MaskSetter2D()
             nd.Should().BeOfValues(99, 99, 99, 3, 4, 5, 99, 99, 99, 9, 10, 11, 99, 99, 99);
         }
 
+        [Ignore("to do fix")]
+        [TestMethod]
+        public void MaskSetter3D()
+        {
+            var nd = np.arange(30).reshape(2, 3, 5);
+            var mask = new NDArray(new bool[] { true, true, false, false, true, true }).reshape(2, 3).MakeGeneric<bool>();
+            nd[mask] = 99;
+        }
+
         [TestMethod]
         public void Compare()
         {