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<html>
<head><title>
HDF5/H5S Draft API Specification
</title></head>
<body>
<hr>
<center>
<a href="RM_H5Front.html">HDF5 Reference Manual</a>
<a href="RM_H5.html">H5</a>
<a href="RM_H5A.html">H5A</a>
<a href="RM_H5D.html">H5D</a>
<a href="RM_H5E.html">H5E</a>
<a href="RM_H5F.html">H5F</a>
<a href="RM_H5G.html">H5G</a>
<a href="RM_H5P.html">H5P</a>
H5S
<a href="RM_H5T.html">H5T</a>
<a href="RM_H5Z.html">H5Z</a>
<a href="Glossary.html">Glossary</a>
</center>
<hr>
<center>
<h1>H5S: Dataspace Interface</h1>
</center>
<h2>Dataspace Object API Functions</h2>
These functions create and manipulate the dataspace in which to store the
elements of a dataset.
<table border=0>
<tr><td valign=top>
<ul>
<li><a href="#Dataspace-Create">H5Screate</a>
<li><a href="#Dataspace-CreateSimple">H5Screate_simple</a>
<li><a href="#Dataspace-Copy">H5Scopy</a>
<li><a href="#Dataspace-SelectNpoints">H5Sselect_npoints</a>
<li><a href="#Dataspace-SelectElements">H5Sselect_elements</a>
</ul>
</td><td> </td><td valign=top>
<ul>
<li><a href="#Dataspace-ExtentNpoints">H5Sextent_npoints</a>
<li><a href="#Dataspace-ExtentNdims">H5Sextent_ndims</a>
<li><a href="#Dataspace-ExtentDims">H5Sextent_dims</a>
<li><a href="#Dataspace-GetClass">H5Sget_class</a>
</ul>
</td><td> </td><td valign=top>
<ul>
<li><a href="#Dataspace-SetExtentSimple">H5Sset_extent_simple</a>
<li><a href="#Dataspace-IsSimple">H5Sis_simple</a>
<li><a href="#Dataspace-SelectHyperslab">H5Sselect_hyperslab</a>
<li><a href="#Dataspace-Close">H5Sclose</a>
</ul>
</td></tr>
</table>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-Create">H5Screate</a>
<dt><strong>Signature:</strong>
<dd><em>hid_t</em> <code>H5Screate</code>(<em>H5S_class_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
<dd>Creates a new dataspace of a specified type.
<dt><strong>Description:</strong>
<dd><code>H5Screate</code> creates a new dataspace of a particular
<code>type</code>.
The types currently supported are <code>H5S_SCALAR</code>,
<code>H5S_SIMPLE</code>, and <code>H5S_NONE</code>;
others are planned to be added later. The <code>H5S_NONE</code>
dataspace can only hold a selection, not an extent.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>H5S_class_t</em> <code>type</code>
<dd>The type of dataspace to be created.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace identifier if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-CreateSimple">H5Screate_simple</a>
<dt><strong>Signature:</strong>
<dd><em>hid_t</em> <code>H5Screate_simple</code>(<em>int</em> <code>rank</code>,
<em>const hsize_t *</em> <code>dims</code>,
<em>const hsize_t *</em> <code>maxdims</code>
)
<dt><strong>Purpose:</strong>
<dd>Creates a new simple data space and opens it for access.
<dt><strong>Description:</strong>
<dd><code>H5Screate_simple</code> creates a new simple data space
and opens it for access. The <code>rank</code> is the number of
dimensions used in the dataspace.
The <code>dims</code> argument is the size
of the simple dataset and the <code>maxdims</code> argument is
the upper limit on the size of the dataset. <code>maxdims</code>
may be the null pointer in which case the upper limit is the
same as <code>dims</code>. If an element of <code>maxdims</code>
is zero then the corresponding dimension is unlimited, otherwise
no element of <code>maxdims</code> should be smaller than the
corresponding element of <code>dims</code>. The dataspace
identifier returned from this function should be released with
<code>H5Sclose</code> or resource leaks will occur.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>int</em> <code>rank</code>
<dd>Number of dimensions of dataspace.
<dt><em>const hsize_t *</em> <code>dims</code>
<dd>An array of the size of each dimension.
<dt><em>const hsize_t *</em> <code>maxdims</code>
<dd>An array of the maximum size of each dimension.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace identifier if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-Copy">H5Scopy</a>
<dt><strong>Signature:</strong>
<dd><em>hid_t </em><code>H5Scopy</code>(<em>hid_t </em><code>space_id</code>
)
<dt><strong>Purpose:</strong>
<dd>Creates an exact copy of a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Scopy</code> creates a new dataspace which is an exact
copy of the dataspace identified by <code>space_id</code>.
The dataspace identifier returned from this function should be
released with <code>H5Sclose</code> or resource leaks will occur.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Identifier of dataspace to copy.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace identifier if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-SelectElements">H5Sselect_elements</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5Sselect_elements</code>(<em>hid_t </em><code>space_id</code>,
<em>dh5s_selopt_t</em> <code>op</code>,
<em>const size_t</em> <code>num_elements</code>,
<em>const hssize_t *</em><code>coord</code>[ ]
)
<dt><strong>Purpose:</strong>
<dd>Selects array elements to be included in the selection for a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sselect_elements</code> selects array elements to be
included in the selection for the <code>space_id</code>
dataspace. The number of elements selected must be set with
the <code>num_elements</code>. The <code>coord</code> array
is a two-dimensional array of size <em>dataspace rank</em>
by <code>num_elements</code> (ie. a list of coordinates in
the array). The order of the element coordinates in the
<code>coord</code> array also specifies the order in which
the array elements are iterated through when I/O is performed.
Duplicate coordinate locations are not checked for.
<P>
The selection operator <code>op</code> determines how the
new selection is to be combined with the previously existing
selection for the dataspace. Currently, only the
<code>H5S_SELECT_SET</code> operator is supported, which
replaces the existing selection with the parameters from
this call. When operators other than <code>H5S_SELECT_SET</code>
are used to combine a new selection with an existing selection,
the selection ordering is reset to 'C' array ordering.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Identifier of the dataspace.
<dt><em>dh5s_selopt_t</em> <code>op</code>
<dd>operator specifying how the new selection is to be
combined with the existing selection for the dataspace.
<dt><em>const size_t</em> <code>num_elements</code>
<dd>Number of elements to be selected.
<dt><em>const hssize_t *</em><code>coord</code>[ ]
<dd>A 2-dimensional array specifying the coordinates of the
elements being selected.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns SUCCEED (0) if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-ExtentNpoints">H5Sextent_npoints</a>
<dt><strong>Signature:</strong>
<dd><em>hsize_t</em> <code>H5Sextent_npoints</code>(<em>hid_t </em><code>space_id</code>)
<dt><strong>Purpose:</strong>
<dd>Determines the number of elements in a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sextent_npoints</code> determines the number of elements
in a dataspace. For example, a simple 3-dimensional dataspace
with dimensions 2, 3, and 4 would have 24 elements.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>ID of the dataspace object to query
</dl>
<dt><strong>Returns:</strong>
<dd>Returns the number of elements in the dataspace if successful;
otherwise returns 0.
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-SelectNpoints">H5Sselect_npoints</a>
<dt><strong>Signature:</strong>
<dd><em>hsize_t</em> <code>H5Sselect_npoints</code>(<em>hid_t</em> <code>space_id</code>)
<dt><strong>Purpose:</strong>
<dd>Determines the number of elements in a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sselect_npoints</code> determines the number of elements
in the current selection of a dataspace.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Dataspace identifier.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace identifier if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-ExtentNdims">H5Sextent_ndims</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Sextent_ndims</code>(<em>hid_t</em> <code>space_id</code>)
<dt><strong>Purpose:</strong>
<dd>Determines the dimensionality of a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sextent_ndims</code> determines the dimensionality (or rank)
of a dataspace.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Identifier of the dataspace
</dl>
<dt><strong>Returns:</strong>
<dd>Returns the number of dimensions in the dataspace if successful;
otherwise FAIL (-1)
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-ExtentDims">H5Sextent_dims</a>
<dt><strong>Signature:</strong>
<dd><em>int</em> <code>H5Sextent_dims</code>(<em>hid_t</em> <code>space_id</code>,
<em>hsize_t *</em><code>dims</code>,
<em>hsize_t *</em><code>maxdims</code>
)
<dt><strong>Purpose:</strong>
<dd>Retrieves dataspace dimension size and maximum size.
<dt><strong>Description:</strong>
<dd><code>H5Sextent_dims</code> returns the size and maximum sizes
of each dimension of a dataspace through the <code>dims</code>
and <code>maxdims</code> parameters.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>IN: Identifier of the dataspace object to query
<dt><em>hsize_t *</em><code>dims</code>
<dd>OUT: Pointer to array to store the size of each dimension.
<dt><em>hsize_t *</em><code>maxdims</code>
<dd>OUT: Pointer to array to store the maximum size of each dimension.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns the number of dimensions in the dataspace if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-SetExtentSimple">H5Sset_extent_simple</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5S_set_extent_simple</code>(<em>hid_t</em> <code>space_id</code>,
<em>int</em> <code>rank</code>,
<em>const hsize_t *</em><code>current_size</code>,
<em>const hsize_t *</em><code>maximum_size</code>
)
<dt><strong>Purpose:</strong>
<dd>Sets or resets the size of an existing dataspace.
<dt><strong>Description:</strong>
<dd><code>H5S_set_extent_simple</code> sets or resets the size of
an existing dataspace.
<p>
<code>rank</code> is the dimensionality, or number of
dimensions, of the dataspace.
<p>
<code>current_size</code> is an array of size <code>rank</code>
which contains the new size of each dimension in the dataspace.
<code>maximum_size</code> is an array of size <code>rank</code>
which contains the maximum size of each dimension in the
dataspace.
<p>
Any previous extent is removed from the dataspace, the dataspace
type is set to <code>H5S_SIMPLE</code>, and the extent is set as
specified.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Dataspace identifier.
<dt><em>int</em> <code>rank</code>
<dd>Rank, or dimensionality, of the dataspace.
<dt><em>const hsize_t *</em><code>current_size</code>
<dd>Array containing current size of dataspace.
<dt><em>const hsize_t *</em><code>maximum_size</code>
<dd>Array containing maximum size of dataspace.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace identifier if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-IsSimple">H5Sis_simple</a>
<dt><strong>Signature:</strong>
<dd><em>hbool_t </em><code>H5Sis_simple</code>(<em>hid_t </em><code>space_id</code>)
<dt><strong>Purpose:</strong>
<dd>Determines whether a dataspace is a simple dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sis_simple</code> determines whether a dataspace is
a simple dataspace. [Currently, all dataspace objects are simple
dataspaces, complex dataspace support will be added in the future]
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Identifier of the dataspace to query
</dl>
<dt><strong>Returns:</strong>
<dd>Returns TRUE or FALSE if Successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-GetClass">H5Sget_class</a>
<dt><strong>Signature:</strong>
<dd><em>H5S_class_t</em> <code>H5Sget_class</code>(<em>hid_t</em> <code>space_id</code>)
<dt><strong>Purpose:</strong>
<dd>Determine the current class of a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sget_class</code> queries a dataspace to determine the
current class of a dataspace.
<p>
The function returns a class name, one of the following:
<code>H5S_SCALAR</code>,
<code>H5S_SIMPLE</code>, or
<code>H5S_NONE</code>.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Dataspace identifier.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns a dataspace class name if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-SelectHyperslab">H5Sselect_hyperslab</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t</em> <code>H5Sselect_hyperslab</code>(<em>hid_t</em> <code>space_id</code>,
<em>h5s_selopt_t</em><code>op</code>,
<em>const hssize_t *</em><code>start</code>,
<em>const hsize_t *</em><code>stride</code>
<em>const hsize_t *</em><code>count</code>,
<em>const hsize_t *</em><code>block</code>
)
<dt><strong>Purpose:</strong>
<dd>Selects a hyperslab region to add to the current selected region.
<dt><strong>Description:</strong>
<dd><code>H5Sselect_hyperslab</code> selects a hyperslab region
to add to the current selected region for the dataspace
specified by <code>space_id</code>.
<p>
The <code>start</code>, <code>stride</code>, <code>count</code>,
and <code>block</code> arrays must be the same size as the rank
of the dataspace.
<p>
The selection operator <code>op</code> determines how the new
selection is to be combined with the already existing selection
for the dataspace.
<p>
Currently, only the <code>H5S_SELECT_SET</code> operator is
supported; it replaces the existing selection with the
parameters from this call. Overlapping blocks are not
supported with the <code>H5S_SELECT_SET</code> operator.
<P>
The <code>start</code> array determines the starting coordinates
of the hyperslab
to select.
<p>
The <code>stride</code> array chooses array locations
from the dataspace
with each value in the <code>stride</code> array determining how
many elements to move
in each dimension. Setting a value in the <code>stride</code>
array to 1 moves to
each element in that dimension of the dataspace; setting a value of 2 in a
location in the <code>stride</code> array moves to every other
element in that
dimension of the dataspace. In other words, the <code>stride</code>
determines the
number of elements to move from the <code>start</code> location
in each dimension.
Stride values of 0 are not allowed. If the <code>stride</code>
parameter is <code>NULL</code>,
a contiguous hyperslab is selected (as if each value in the
<code>stride</code> array
was set to all 1's).
<p>
The <code>count</code> array determines how many blocks to
select from the dataspace, in each dimension.
<p>
The <code>block</code> array determines
the size of the element block selected from the dataspace.
If the <code>block</code>
parameter is set to <code>NULL</code>, the block size defaults
to a single element
in each dimension (as if the <code>block</code> array was set to all 1's).
<P>
For example, in a 2-dimensional dataspace, setting
<code>start</code> to [1,1],
<code>stride</code> to [4,4], <code>count</code> to [3,7], and
<code>block</code> to [2,2] selects
21 2x2 blocks of array elements starting with location (1,1) and selecting
blocks at locations (1,1), (5,1), (9,1), (1,5), (5,5), etc.
<P>
Regions selected with this function call default to C order iteration when
I/O is performed.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>IN: Identifier of dataspace selection to modify
<dt><em>H5S_seloper_t</em> <code>op</code>
<dd>IN: Operation to perform on current selection.
<dt><em>const hssize_t *</em><code>start</code>
<dd>IN: Offset of start of hyperslab
<dt><em>const hsize_t *</em><code>count</code>
<dd>IN: Number of blocks included in hyperslab.
<dt><em>const hsize_t *</em><code>stride</code>
<dd>IN: Hyperslab stride.
<dt><em>const hsize_t *</em><code>block</code>
<dd>IN: Size of block in hyperslab.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns SUCCEED (0) if successful;
otherwise FAIL (-1).
</dl>
<hr>
<dl>
<dt><strong>Name:</strong> <a name="Dataspace-Close">H5Sclose</a>
<dt><strong>Signature:</strong>
<dd><em>herr_t </em><code>H5Sclose</code>(<em>hid_t </em><code>space_id</code>
)
<dt><strong>Purpose:</strong>
<dd>Releases and terminates access to a dataspace.
<dt><strong>Description:</strong>
<dd><code>H5Sclose</code> releases a dataspace.
Further access through the dataspace identifier is illegal.
Failure to release a dataspace with this call will
result in resource leaks.
<dt><strong>Parameters:</strong>
<dl>
<dt><em>hid_t</em> <code>space_id</code>
<dd>Identifier of dataspace to release.
</dl>
<dt><strong>Returns:</strong>
<dd>Returns SUCCEED (0) if successful;
otherwise FAIL (-1).
</dl>
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