[c++/m] Add DataArray getDimensionByIndex

Closes #123

Author: mpsonntag

+nix/DataArray.m

@@ -73,6 +73,21 @@
             dim = nix.RangeDimension(nix_mx(func_name, obj.nix_handle));
         end
 
+        function dim = open_dimension_idx(obj, idx)
+        % Getting the dimension by index starts with 1
+        % instead of 0 compared to all other index functions.
+            func_name = strcat(obj.alias, '::openDimensionIdx');
+            ret = nix_mx(func_name, obj.nix_handle, idx);
+            switch(ret.dimension_type)
+                case 'set'
+                    dim = nix.SetDimension(ret.handle);
+                case 'sampled'
+                    dim = nix.SampledDimension(ret.handle);
+                case 'range'
+                    dim = nix.RangeDimension(ret.handle);
+            end;
+        end
+
         function delCheck = delete_dimensions(obj)
             func_name = strcat(obj.alias, '::deleteDimensions');
             delCheck = nix_mx(func_name, obj.nix_handle);

nix_mx.cc

@@ -247,6 +247,7 @@ void mexFunction(int            nlhs,
         methods->add("DataArray::dataType", nixdataarray::dataType);
         methods->add("DataArray::setDataExtent", nixdataarray::setDataExtent);
         methods->add("DataArray::openSourceIdx", nixdataarray::openSourceIdx);
+        methods->add("DataArray::openDimensionIdx", nixdataarray::openDimensionIdx);
 
         classdef<nix::Source>("Source", methods)
             .desc(&nixsource::describe)

src/nixdataarray.cc

@@ -7,6 +7,7 @@
 // LICENSE file in the root of the Project.
 
 #include "nixdataarray.h"
+#include "nixdimensions.h"
 #include "mkarray.h"
 #include "mex.h"
 
@@ -142,4 +143,31 @@ namespace nixdataarray {
         output.set(0, currObj.getSource(idx));
     }
 
+    void openDimensionIdx(const extractor &input, infusor &output) {
+        nix::DataArray currObj = input.entity<nix::DataArray>(1);
+        nix::ndsize_t idx = (nix::ndsize_t)input.num<double>(2);
+
+        nix::Dimension d = currObj.getDimension(idx);
+
+        struct_builder sb({ 1 }, { "dimension_type", "handle" });
+
+        switch (d.dimensionType()) {
+        case nix::DimensionType::Set:
+            sb.set("set");
+            sb.set(d.asSetDimension());
+            break;
+        case nix::DimensionType::Sample:
+            sb.set("sampled");
+            sb.set(d.asSampledDimension());
+            break;
+        case nix::DimensionType::Range:
+            sb.set("range");
+            sb.set(d.asRangeDimension());
+            break;
+        default: throw std::invalid_argument("unkown dimension type");
+        }
+
+        output.set(0, sb.array());
+    }
+
 } // namespace nixdataarray

src/nixdataarray.h

@@ -43,6 +43,8 @@ namespace nixdataarray {
 
     void openSourceIdx(const extractor &input, infusor &output);
 
+    void openDimensionIdx(const extractor &input, infusor &output);
+
 } // namespace nixdataarray
 
 #endif

tests/TestDataArray.m

@@ -28,6 +28,7 @@
     funcs{end+1} = @test_has_source;
     funcs{end+1} = @test_source_count;
     funcs{end+1} = @test_dimensions;
+    funcs{end+1} = @test_open_dimension_idx;
     funcs{end+1} = @test_dimension_count;
     funcs{end+1} = @test_datatype;
     funcs{end+1} = @test_set_data_extent;
@@ -510,6 +511,24 @@
     assert(isequal(daAliasWa.dataExtent, [3 3]));
 end
 
+function [] = test_open_dimension_idx( varargin )
+%% Test: Open dimension by index
+    fileName = fullfile(pwd, 'tests', 'testRW.h5');
+    f = nix.File(fileName, nix.FileMode.Overwrite);
+    b = f.create_block('daTestBlock', 'test nixBlock');
+    da = b.create_data_array('daTest', 'test nixDataArray', nix.DataType.Double, [1 2]);
+    
+    da.append_set_dimension();
+    da.append_sampled_dimension(200);
+    da.append_range_dimension([1, 2, 3, 4]);
+
+    % for some weird reason getting the dimension by index starts with 1
+    % instead of 0 compared to all other index functions.
+    assert(strcmp(da.open_dimension_idx(1).dimensionType, 'set'));
+    assert(strcmp(da.open_dimension_idx(2).dimensionType, 'sample'));
+    assert(strcmp(da.open_dimension_idx(3).dimensionType, 'range'));
+end
+
 %% Test: Dimension count
 function [] = test_dimension_count( varargin )
     testFile = fullfile(pwd, 'tests', 'testRW.h5');