GH-37597: [MATLAB] Add toMATLAB method to `arrow.array.ChunkedArray…

…` class (#37613) ### Rationale for this change Currently, there is no way to easily convert an `arrow.array.ChunkedArray` into a corresponding MATLAB array, other than (1) manually iterating chunk by chunk, (2) calling `toMATLAB` on each chunk, and then (3) concatenating all of the converted chunks together into one contiguous MATLAB array. It would be helpful to add a toMATLAB method to `arrow.array.ChunkedArray` that abstracts away all of these steps. ### What changes are included in this PR? 1. Added `toMATLAB` method to `arrow.array.ChunkedArray` class 2. Added `preallocateMATLABArray` abstract method to `arrow.type.Type` class. This method is used by the `ChunkedArray` `toMATLAB` to pre-allocate a MATLAB array of the expected class type and shape. This is necessary to ensure `toMATLAB` returns the correct MATLAB array when the `ChunkedArray` has zero chunks. If `toMATLAB` stored the result of calling `toMATLAB` on each chunk in a `cell` array before concatenating the values, `toMATLAB` would return a 0x0 `double` array for zero-chunked arrays. The pre-allocation approach avoids this issue. 3. Implement `preallocateMATLABArray` on all `arrow.type.Type` classes. 4. Added an abstract class `arrow.type.NumericType` that all classes representing numeric data types inherit from. `NumericType` implements `preallocateMATLABArray` for its subclasses. ### Are these changes tested? Yes. Added unit tests to `tChunkedArray.m`. ### Are there any user-facing changes? Yes. Users can now call `toMATLAB` on `ChunkedArray`s. **Example** ```matlab >> a = arrow.array([1 2 NaN 4 5]); >> b = arrow.array([6 7 8 9 NaN 11]); >> c = arrow.array.ChunkedArray.fromArrays(a, b); >> data = toMATLAB(c) data = 1 2 NaN 4 5 6 7 8 9 NaN 11 ``` * Closes: #37597 Authored-by: Sarah Gilmore <sgilmore@mathworks.com> Signed-off-by: Kevin Gurney <kgurney@mathworks.com>
apache · Sep 7, 2023 · 65e2f22 · 65e2f22
1 parent 3b4a6b1
commit 65e2f22
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diff --git a/matlab/src/matlab/+arrow/+array/ChunkedArray.m b/matlab/src/matlab/+arrow/+array/ChunkedArray.m
@@ -60,6 +60,17 @@
             array = traits.ArrayConstructor(proxy);
         end
 
+        function data = toMATLAB(obj)
+            data = preallocateMATLABArray(obj.Type,  obj.Length);
+            startIndex = 1;
+            for ii = 1:obj.NumChunks
+                chunk = obj.chunk(ii);
+                endIndex = startIndex + chunk.Length - 1;
+                data(startIndex:endIndex) = toMATLAB(chunk);
+                startIndex = endIndex + 1;
+            end
+        end
+
         function tf = isequal(obj, varargin)
             narginchk(2, inf);
 

diff --git a/matlab/src/matlab/+arrow/+type/BooleanType.m b/matlab/src/matlab/+arrow/+type/BooleanType.m
@@ -32,4 +32,10 @@
             groups = matlab.mixin.util.PropertyGroup(targets);
         end
     end
+
+    methods(Hidden)
+        function data = preallocateMATLABArray(~, length)
+            data = false([length 1]);
+        end
+    end
 end
diff --git a/matlab/src/matlab/+arrow/+type/DateType.m b/matlab/src/matlab/+arrow/+type/DateType.m
@@ -42,4 +42,10 @@
         end
     end
 
+    methods(Hidden)
+        function data = preallocateMATLABArray(~, length)
+            data = NaT([length 1]);
+        end
+    end
+
 end
diff --git a/matlab/src/matlab/+arrow/+type/Float32Type.m b/matlab/src/matlab/+arrow/+type/Float32Type.m
@@ -1,3 +1,5 @@
+%FLOAT32TYPE Type class for float32 data.
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Float32Type < arrow.type.FixedWidthType
-%FLOAT32TYPE Type class for float32 data.
+classdef Float32Type < arrow.type.NumericType
 
     methods 
         function obj = Float32Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Float32Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end
diff --git a/matlab/src/matlab/+arrow/+type/Float64Type.m b/matlab/src/matlab/+arrow/+type/Float64Type.m
@@ -1,3 +1,5 @@
+%FLOAT64TYPE Type class for float64 data. 
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Float64Type < arrow.type.FixedWidthType
-%FLOAT64Type Type class for float64 data. 
+classdef Float64Type < arrow.type.NumericType
 
     methods 
         function obj = Float64Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Float64Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end
diff --git a/matlab/src/matlab/+arrow/+type/Int16Type.m b/matlab/src/matlab/+arrow/+type/Int16Type.m
@@ -1,3 +1,5 @@
+%INT16TYPE Type class for int16 data. 
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Int16Type < arrow.type.FixedWidthType
-%INT16TYPE Type class for int8 data. 
+classdef Int16Type < arrow.type.NumericType
 
     methods 
         function obj = Int16Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Int16Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end

diff --git a/matlab/src/matlab/+arrow/+type/Int32Type.m b/matlab/src/matlab/+arrow/+type/Int32Type.m
@@ -1,3 +1,5 @@
+%INT32TYPE Type class for int32 data.
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Int32Type < arrow.type.FixedWidthType
-%INT32TYPE Type class for int32 data.
+classdef Int32Type < arrow.type.NumericType
 
     methods 
         function obj = Int32Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Int32Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end

diff --git a/matlab/src/matlab/+arrow/+type/Int64Type.m b/matlab/src/matlab/+arrow/+type/Int64Type.m
@@ -1,3 +1,5 @@
+%INT64TYPE Type class for int64 data.
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Int64Type < arrow.type.FixedWidthType
-%INT64TYPE Type class for int64 data.
+classdef Int64Type < arrow.type.NumericType
 
     methods 
         function obj = Int64Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Int64Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end
diff --git a/matlab/src/matlab/+arrow/+type/Int8Type.m b/matlab/src/matlab/+arrow/+type/Int8Type.m
@@ -1,3 +1,5 @@
+%INT8TYPE Type class for int8 data. 
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,23 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef Int8Type < arrow.type.FixedWidthType
-%INT8TYPE Type class for int8 data. 
+classdef Int8Type < arrow.type.NumericType
 
     methods 
         function obj = Int8Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.Int8Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end

diff --git a/matlab/src/matlab/+arrow/+type/NumericType.m b/matlab/src/matlab/+arrow/+type/NumericType.m
@@ -0,0 +1,43 @@
+%NUMERICTYPE Type class for numeric data
+
+% Licensed to the Apache Software Foundation (ASF) under one or more
+% contributor license agreements.  See the NOTICE file distributed with
+% this work for additional information regarding copyright ownership.
+% The ASF licenses this file to you 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
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% 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.
+
+classdef NumericType < arrow.type.FixedWidthType
+
+    methods
+        function obj = NumericType(proxy)
+            arguments
+                proxy(1, 1) libmexclass.proxy.Proxy
+            end
+
+            obj@arrow.type.FixedWidthType(proxy);
+        end
+    end
+
+    methods(Hidden)
+        function data = preallocateMATLABArray(obj, length)
+            traits = arrow.type.traits.traits(obj.ID);
+            data = zeros([length 1], traits.MatlabClassName);
+        end
+    end
+
+    methods (Access=protected)
+        function groups = getDisplayPropertyGroups(~)
+            targets = "ID";
+            groups = matlab.mixin.util.PropertyGroup(targets);
+        end
+    end
+end
diff --git a/matlab/src/matlab/+arrow/+type/StringType.m b/matlab/src/matlab/+arrow/+type/StringType.m
@@ -32,5 +32,11 @@
             groups = matlab.mixin.util.PropertyGroup(targets);
         end
     end
+
+    methods(Hidden)
+        function data = preallocateMATLABArray(~, length)
+            data = strings(length, 1);
+        end
+    end
 end
 
diff --git a/matlab/src/matlab/+arrow/+type/TimeType.m b/matlab/src/matlab/+arrow/+type/TimeType.m
@@ -42,4 +42,11 @@
         end
     end
 
+    methods(Hidden)
+        function data = preallocateMATLABArray(~, length)
+            data = NaN([length 1]);
+            data = seconds(data);
+        end
+    end
+
 end
diff --git a/matlab/src/matlab/+arrow/+type/TimestampType.m b/matlab/src/matlab/+arrow/+type/TimestampType.m
@@ -47,4 +47,10 @@
             groups = matlab.mixin.util.PropertyGroup(targets);
         end
     end
+
+    methods(Hidden)
+        function data = preallocateMATLABArray(obj, length)
+            data = NaT([length, 1], TimeZone=obj.TimeZone);
+        end
+    end
 end
diff --git a/matlab/src/matlab/+arrow/+type/Type.m b/matlab/src/matlab/+arrow/+type/Type.m
@@ -93,6 +93,10 @@ function displayScalarHandleToDeletedObject(obj)
         end
     end
 
+    methods(Abstract, Hidden)
+        data = preallocateMATLABArray(obj, length)
+    end
+
     methods (Sealed)
         function tf = isequal(obj, varargin)
 

diff --git a/matlab/src/matlab/+arrow/+type/UInt16Type.m b/matlab/src/matlab/+arrow/+type/UInt16Type.m
@@ -1,3 +1,5 @@
+%UINT16TYPE Type class for uint16 data.
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,24 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef UInt16Type < arrow.type.FixedWidthType
-%UINT16TYPE Type class for uint16 data.
+classdef UInt16Type < arrow.type.NumericType
 
     methods 
         function obj = UInt16Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.UInt16Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end
diff --git a/matlab/src/matlab/+arrow/+type/UInt32Type.m b/matlab/src/matlab/+arrow/+type/UInt32Type.m
@@ -1,3 +1,5 @@
+%UINT32TYPE Type class for uint32 data.
+
 % Licensed to the Apache Software Foundation (ASF) under one or more
 % contributor license agreements.  See the NOTICE file distributed with
 % this work for additional information regarding copyright ownership.
@@ -13,24 +15,15 @@
 % implied.  See the License for the specific language governing
 % permissions and limitations under the License.
 
-classdef UInt32Type < arrow.type.FixedWidthType
-%UINT32TYPE Type class for uint32 data.
+classdef UInt32Type < arrow.type.NumericType
 
     methods 
         function obj = UInt32Type(proxy)
             arguments
                 proxy(1, 1) libmexclass.proxy.Proxy {validate(proxy, "arrow.type.proxy.UInt32Type")}
             end
             import arrow.internal.proxy.validate
-            obj@arrow.type.FixedWidthType(proxy);
-        end
-    end
-
-
-    methods (Access=protected)
-        function groups = getDisplayPropertyGroups(~)
-            targets = "ID";
-            groups = matlab.mixin.util.PropertyGroup(targets);
+            obj@arrow.type.NumericType(proxy);
         end
     end
 end