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345e07fc11
Purpose:
[is this a bug fix? feature? ...]
Description:
[describe the bug, or describe the new feature, etc]
Solution:
[details about the changes, algorithm, etc...]
[Please as detail as you can since your own explanation is
better than others guessing it from the code.]
Platforms tested:
[machines you have tested the changed version. This is absolute
important. Test it out on at least two or three different platforms
such as Big-endian-32bit (SUN/IRIX), little-endian-32(LINUX) and
64-bit (IRIX64/UNICOS/DEC-ALPHA) would be good.]
270 lines
7.5 KiB
HTML
270 lines
7.5 KiB
HTML
<HTML><HEAD>
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<TITLE>HDF5 Tutorial - Selecting Individual Points and Copying a Dataspace
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</TITLE>
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</HEAD>
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<body bgcolor="#ffffff">
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<!-- BEGIN MAIN BODY -->
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<A HREF="http://www.ncsa.uiuc.edu/"><img border=0
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src="http://www.ncsa.uiuc.edu/Images/NCSAhome/footerlogo.gif"
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width=78 height=27 alt="NCSA"><P></A>
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[ <A HREF="title.html"><I>HDF5 Tutorial Top</I></A> ]
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<H1>
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<BIG><BIG><BIG><FONT COLOR="#c101cd">Selecting Individual Points and Copying
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a Dataspace</FONT>
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</BIG></BIG></BIG></H1>
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<hr noshade size=1>
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<BODY>
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<H2>Contents:</H2>
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<UL>
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<LI> <A HREF="#def">Description</A>
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<LI> Programming Example
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<UL>
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<LI> <A HREF="#desc">Description</A>
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<LI> <A HREF="#rem">Remarks</A>
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<LI> <A HREF="#fc">File Contents</A>
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</UL>
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</UL>
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<HR>
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<A NAME="def">
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<H2>Description</h2>
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You can select independent points to read from or write to in a
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dataspace by use of the <CODE>H5Sselect_elements</CODE> /
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<CODE>h5sselect_elements_f</CODE> function.
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<P>
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The <CODE>H5Scopy</CODE> / <CODE>h5scopy_f</CODE> function allows
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you to make an exact copy of a dataspace.
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This can reduce the number of function calls needed when
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selecting a dataspace.
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<P>
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<H2> Programming Example</H2>
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<A NAME="desc">
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<H3><U>Description</U></H3>
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This example shows how to use <CODE>H5Sselect_elements</CODE> /
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<CODE>h5sselect_elements_f</CODE>
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to select individual points in a dataset and how to use
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<CODE>H5Scopy</CODE> / <CODE>h5scopy_f</CODE>
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to make a copy of a dataspace.
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<UL>
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[ <A HREF="examples/h5_copy.c">C example</A> ]
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- <code>h5_copy.c</code><BR>
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[ <A HREF="examples/selectele.f90">FORTRAN example</A> ]
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- <code>selectele.f90</code><BR>
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[ <A HREF="examples/java/Copy.java">Java example</A> ]
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- <code>Copy.java</code>
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</UL>
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<B>NOTE:</B> To download a tar file of the examples, including a Makefile,
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please go to the <A HREF="references.html">References</A> page.
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<A NAME="rem">
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<H3><U>Remarks</U></H3>
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<UL>
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<LI><CODE>H5Sselect_elements</CODE> / <CODE>h5sselect_elements_f</CODE>
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selects array elements to be
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included in the selection for a dataspace:
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<P>
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<I><B>C</B></I>:
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<pre>
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herr_t H5Sselect_elements (hid_t space_id, H5S_seloper_t operator,
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size_t num_elements,
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const hssize_t **coord )
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</pre>
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<P>
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<I><B>FORTRAN</B></I>:
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<pre>
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h5sselect_elements_f (space_id, operator, num_elements, coord, hdferr)
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space_id IN: INTEGER(HID_T)
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operator IN: INTEGER
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num_elements IN: INTEGER
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coord IN: INTEGER(HSSIZE_T), DIMENSION(*,*)
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hdferr OUT: INTEGER
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</pre>
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<P>
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<UL>
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<LI>The <I>space_id</I> parameter is the dataspace identifier.
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<P>
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<LI>The <I>operator</I> parameter can be set to one of the following values:
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<dir><DL>
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<dt><CODE>H5S_SELECT_SET</CODE> (<CODE>H5S_SELECT_SET_F</CODE> in FORTRAN)
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<dd>Replace the existing selection with the parameters from this call.
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Overlapping blocks are not supported with this operator.
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<dt><CODE>H5S_SELECT_OR</CODE> (<CODE>H5S_SELECT_OR_F</CODE> in FORTRAN)
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<dd>Add the new selection to the existing selection.
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</DL></dir>
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<P>
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<LI>The <I>coord</I> array is a two-dimensional array of size
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<code><em>NUMP</em> x <em>RANK</em></code> in C
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(<code><em>RANK</em> x <em>NUMP</em></code> in FORTRAN)
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where <code><em>NUMP</em></code> is the number of selected points
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and <code><em>RANK</em></code> is the rank of the dataset.
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Note that these coordinates are 0-based in C and 1-based in FORTRAN.
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<p>
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Consider the non-zero elements of the following array:
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<pre>
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0 59 0 53
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0 0 0 0
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0 0 1 0 </pre>
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In C, the <em>coord</em> array selecting these points would be as follows:
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<pre>
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0 1
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0 3
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2 2 </pre>
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While in FORTRAN, the <em>coord</em> array would be as follows:
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<pre>
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1 1 3
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2 4 3 </pre>
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<P>
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<LI>In C, this function returns a non-negative value if successful and
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a negative value otherwise. In FORTRAN, the value returned in <I>hdferr</I>
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indicates whether it was successful (0) or not (-1).
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</UL>
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<P>
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<LI><CODE>H5Scopy</CODE> / <CODE>h5scopy_f</CODE> creates an exact copy of a dataspace:
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<P>
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<I><B>C</B></I>:
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<PRE>
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hid_t H5Scopy (hid_t space_id)
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</PRE>
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<I><B>FORTRAN</B></I>:
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<PRE>
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h5scopy_f (space_id, new_space_id, hdferr)
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space_id IN: INTEGER(HID_T)
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new_space_id OUT: INTEGER(HID_T)
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hdferr OUT: INTEGER
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</PRE>
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<P>
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<UL>
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<LI>The <I>space_id</I> parameter is the dataspace identifier to copy.
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<P>
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<LI>In C, the identifier to the dataspace's copy is returned if the
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function is successful and a negative value is returned if not. In
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FORTRAN, the new dataspace identifier is returned in <I>new_space_id</I>
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and the return value is returned in <I>hdferr</I> ( 0 if successful and
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-1 if not).
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</UL>
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</UL>
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</UL>
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<P>
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<A NAME="fc">
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<H3><U>File Contents</U></H3>
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Following is the DDL for <I>copy1.h5</I> and <I>copy2.h5</I>, as viewed with
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the following commands:<br>
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<code>h5dump copy1.h5</code> <br>
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<code>h5dump copy2.h5</code>
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<P>
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<HR>
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<B><I><U>C</U></B></I>:<P>
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<B>Fig. S.1a</B> <I><code>copy1.h5</code> in DDL</I>
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<PRE>
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HDF5 "copy1.h5" {
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GROUP "/" {
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DATASET "Copy1" {
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DATATYPE { H5T_STD_I32BE }
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DATASPACE { SIMPLE ( 3, 4 ) / ( 3, 4 ) }
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DATA {
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0, 59, 0, 53,
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0, 0, 0, 0,
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0, 0, 0, 0
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}
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}
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}
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}
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</PRE>
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<B>Fig. S.1b</B> <I><code>copy2.h5</code> in DDL</I>
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<PRE>
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HDF5 "copy2.h5" {
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GROUP "/" {
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DATASET "Copy2" {
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DATATYPE { H5T_STD_I32BE }
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DATASPACE { SIMPLE ( 3, 4 ) / ( 3, 4 ) }
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DATA {
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1, 59, 1, 53,
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1, 1, 1, 1,
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1, 1, 1, 1
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}
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}
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}
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}
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</PRE>
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<HR>
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<I><B><U>FORTRAN</U></B></I>:<P>
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<B>Fig. S.2a</B> <I><code>copy1.h5</code> in DDL</I>
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<PRE>
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HDF5 "copy1.h5" {
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GROUP "/" {
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DATASET "Copy1" {
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DATATYPE { H5T_STD_I32BE }
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DATASPACE { SIMPLE ( 4, 3 ) / ( 4, 3 ) }
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DATA {
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0, 0, 0,
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53, 0, 0,
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0, 0, 0,
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59, 0, 0
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}
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}
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}
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}
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</PRE>
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<B>Fig. S.2b</B> <I><code>copy2.h5</code> in DDL</I>
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<PRE>
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HDF5 "copy2.h5" {
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GROUP "/" {
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DATASET "Copy2" {
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DATATYPE { H5T_STD_I32BE }
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DATASPACE { SIMPLE ( 4, 3 ) / ( 4, 3 ) }
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DATA {
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1, 1, 1,
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53, 1, 1,
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1, 1, 1,
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59, 1, 1
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}
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}
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}
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}
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</PRE>
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<!-- BEGIN FOOTER INFO -->
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<P><hr noshade size=1>
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<font face="arial,helvetica" size="-1">
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<a href="http://www.ncsa.uiuc.edu/"><img border=0
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src="http://www.ncsa.uiuc.edu/Images/NCSAhome/footerlogo.gif"
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width=78 height=27 alt="NCSA"><br>
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The National Center for Supercomputing Applications</A><br>
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<a href="http://www.uiuc.edu/">University of Illinois
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at Urbana-Champaign</a><br>
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<br>
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<!-- <A HREF="helpdesk.mail.html"> -->
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<A HREF="mailto:hdfhelp@ncsa.uiuc.edu">
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hdfhelp@ncsa.uiuc.edu</A>
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<br>
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Describes HDF5 Release 1.2.2, June 2000
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<BR> <H6>Last Modified: April 5, 2000</H6><BR>
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<!-- modified by Barbara Jones - bljones@ncsa.uiuc.edu -->
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<!-- modified by Frank Baker - fbaker@ncsa.uiuc.edu -->
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</FONT>
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<BR>
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<!-- <A HREF="mailto:hdfhelp@ncsa.uiuc.edu"> -->
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</BODY>
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</HTML>
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