h5write scalar variables to scalar dataset

Author: scivision

+stdlib/+hdf5nc/TestHDF5.m

@@ -101,11 +101,10 @@ function test_get_variables(tc)
 
 function test_exists(tc, vars)
 import stdlib.hdf5nc.h5exists
-import matlab.unittest.constraints.IsScalar
 basic = tc.TestData.basic;
 
 e = h5exists(basic, "/" + vars);
-tc.verifyThat(e, IsScalar)
+tc.verifyTrue(isscalar(e))
 tc.verifyTrue(e)
 
 % vector
@@ -124,15 +123,14 @@ function test_exists(tc, vars)
 
 function test_size(tc)
 import stdlib.hdf5nc.h5size
-import matlab.unittest.constraints.IsScalar
 basic = tc.TestData.basic;
 
 s = h5size(basic, '/A0');
-tc.verifyThat(s, IsScalar)
+tc.verifyTrue(isscalar(s))
 tc.verifyEqual(s, 1)
 
 s = h5size(basic, '/A1');
-tc.verifyThat(s, IsScalar)
+tc.verifyTrue(isscalar(s))
 tc.verifyEqual(s, 2)
 
 s = h5size(basic, '/A2');
@@ -155,11 +153,10 @@ function test_size(tc)
 
 
 function test_read(tc)
-import matlab.unittest.constraints.IsScalar
 basic = tc.TestData.basic;
 
 s = h5read(basic, '/A0');
-tc.verifyThat(s, IsScalar)
+tc.verifyTrue(isscalar(s))
 tc.verifyEqual(s, 42)
 
 s = h5read(basic, '/A1');
@@ -218,11 +215,11 @@ function test_string(tc, str)
 
 function test_file_missing(tc)
 
-tc.verifyError(@() stdlib.hdf5nc.h5exists(tempname,""), 'hdf5nc:h5variables:fileNotFound')
+tc.verifyError(@() stdlib.hdf5nc.h5exists(tempname,"/bad"), 'hdf5nc:h5variables:fileNotFound')
 tc.verifyError(@() stdlib.hdf5nc.h5variables(tempname), 'hdf5nc:h5variables:fileNotFound')
-tc.verifyError(@() stdlib.hdf5nc.h5size(tempname,""), 'hdf5nc:h5size:fileNotFound')
+tc.verifyError(@() stdlib.hdf5nc.h5size(tempname,"/bad"), 'hdf5nc:h5size:fileNotFound')
 [~,badname] = fileparts(tempname);
-tc.verifyError(@() stdlib.hdf5nc.h5save(badname,"",0), 'hdf5nc:h5save:fileNotFound')
+tc.verifyError(@() stdlib.hdf5nc.h5save(badname,"/bad",0), 'hdf5nc:h5save:fileNotFound')
 end
 
 function test_real_only(tc)

+stdlib/+hdf5nc/h5save.m

@@ -14,6 +14,10 @@ function h5save(filename, varname, A, opts)
 import stdlib.fileio.expanduser
 import stdlib.hdf5nc.h5exists
 
+if strlength(varname) < 2
+  error("MATLAB:expectedNonempty", "variable name must start with / and be non-empty")
+end
+
 if isnumeric(A)
   mustBeReal(A)
 end
@@ -77,6 +81,31 @@ function new_file(filename, varname, A, sizeA)
   error('hdf5nc:h5save:fileNotFound', '%s is not a folder, cannot create %s', folder, filename)
 end
 
+if isscalar(A) && ~isstring(A) && ~isempty(varname)
+  dcpl = 'H5P_DEFAULT';
+
+  if isfile(filename)
+    fid = H5F.open(filename, 'H5F_ACC_RDWR', dcpl);
+  else
+    fid = H5F.create(filename);
+  end
+
+  create_hdf5_group(fid, varname);
+
+  space_id = H5S.create('H5S_SCALAR');
+  t = class2h5t(A);
+  type_id = H5T.copy(t);
+  dset_id = H5D.create(fid, varname, type_id, space_id, dcpl);
+  H5D.write(dset_id,'H5ML_DEFAULT','H5S_ALL','H5S_ALL', dcpl, A);
+
+  H5S.close(space_id);
+  H5T.close(type_id);
+  H5D.close(dset_id);
+  H5F.close(fid);
+
+  return
+end
+
 if isvector(A)
   h5create(filename, varname, sizeA, 'DataType', class(A))
 else
@@ -91,7 +120,45 @@ function new_file(filename, varname, A, sizeA)
 
 end % function
 
-% Copyright 2020 Michael Hirsch, Ph.D.
+
+function t = class2h5t(A)
+% gets HDF5 H5T of variable A
+
+switch class(A)
+  case 'double', t = 'H5T_NATIVE_DOUBLE';
+  case 'single', t = 'H5T_NATIVE_FLOAT';
+  case 'int32', t = 'H5T_STD_I32LE';
+  case 'int64', t = 'H5T_STD_I64LE';
+  otherwise, error('h5save:class2h5t: unknown data class %s', class(A))
+end
+
+end
+
+
+function create_hdf5_group(fid, name)
+
+grps = split(name, "/");
+if length(grps) < 3
+  return
+end
+
+plist = 'H5P_DEFAULT';
+groot = H5G.open(fid, "/");
+
+for i = 0:length(grps) - 3
+  n = join(grps(1:i+2), "/");
+
+  if ~H5L.exists(groot, n, plist)
+    gid = H5G.create(fid, n, plist, plist, plist);
+    H5G.close(gid)
+  end
+end % for
+
+H5G.close(groot)
+end % function
+
+
+% Copyright 2020 Michael Hirsch
 
 % Licensed under the Apache License, Version 2.0 (the "License");
 % you may not use this file except in compliance with the License.

+stdlib/+hdf5nc/h5size.m

@@ -27,6 +27,11 @@
   error("hdf5nc:h5size:fileNotFound", "%s not found.", file)
 end
 
-fsize = h5info(file, variable).Dataspace.Size;
+dsi = h5info(file, variable).Dataspace;
+if dsi.Type == "scalar"
+  fsize = 1;
+else
+  fsize = dsi.Size;
+end
 
 end

Readme.md

@@ -31,8 +31,6 @@ TestAll
 import stdlib.hdf5nc.*
 ```
 
-Matlab R2021a uses HDF5 1.8.12.
-
 ```matlab
 [major,minor,rel] = H5.get_libversion()
 ```
@@ -68,9 +66,6 @@ h5variables(filename)
 import stdlib.hdf5nc.*
 ```
 
-
-Matlab R2021a uses NetCDF4 4.7.3.
-
 ```matlab
 netcdf.inqLibVers
 ```