[svn-r3083] Renamed chunks.C to chunks.cpp

1 files changed, 206 insertions, 0 deletions

diff --git a/c++/examples/chunks.cpp b/c++/examples/chunks.cpp
new file mode 100644
index 0000000..f560b16
--- /dev/null
+++ b/c++/examples/chunks.cpp
@@ -0,0 +1,206 @@
+/*  
+ *   This example shows how to read data from a chunked dataset.
+ *   We will read from the file created by extend.C 
+ */
+ 
+#include <string>
+#ifndef H5_NO_NAMESPACE
+using namespace std;
+#endif
+
+#ifdef OLD_HEADER_FILENAME
+#include <iostream.h>
+#else
+#include <iostream>
+#endif
+#include "H5Cpp.h"
+
+#ifndef H5_NO_NAMESPACE
+using namespace H5;
+#endif
+
+const string FILE_NAME( "SDSextendible.h5" );
+const string DATASET_NAME( "ExtendibleArray" );
+const int      NX = 10;
+const int      NY = 5;
+const int      RANK = 2;
+const int      RANKC = 1;
+
+int main (void)
+{
+   hsize_t	i, j;
+
+   // Try block to detect exceptions raised by any of the calls inside it
+   try
+   {
+      /*
+       * Open the file and the dataset.
+       */
+      H5File file( FILE_NAME, H5F_ACC_RDONLY );
+      DataSet dataset = file.openDataSet( DATASET_NAME );
+ 
+      /*
+       * Get dataset rank and dimension.
+       */
+      // Get filespace first.
+      DataSpace filespace = dataset.getSpace();
+
+      // Get number of dimensions in the file dataspace
+      int rank = filespace.getSimpleExtentNdims();
+
+      // Get and print the dimension sizes of the file dataspace
+      hsize_t     dims[2];       // dataset dimensions 
+      rank = filespace.getSimpleExtentDims( dims );
+      cout << "dataset rank = " << rank << ", dimensions " 
+	<< (unsigned long)(dims[0]) << " x " << (unsigned long)(dims[1])
+	<< endl;
+
+      /*
+       * Get creation properties list.
+       */
+      DSetCreatPropList cparms = dataset.getCreatePlist(); 
+
+      /* 
+       * Check if dataset is chunked.
+       */
+      hsize_t     chunk_dims[2];
+      int         rank_chunk;
+      if( H5D_CHUNKED == cparms.getLayout() )
+      {
+	 /*
+	  * Get chunking information: rank and dimensions
+	  */
+	 rank_chunk = cparms.getChunk( 2, chunk_dims);
+         cout << "chunk rank " << rank_chunk << "dimensions " 
+	   << (unsigned long)(chunk_dims[0]) << " x " 
+	   << (unsigned long)(chunk_dims[1]) << endl;
+      }
+ 
+      /*
+       * Define the memory space to read dataset.
+       */
+      DataSpace mspace1( RANK, dims );
+ 
+      /*
+       * Read dataset back and display.
+       */
+      int data_out[NX][NY];  // buffer for dataset to be read
+      dataset.read( data_out, PredType::NATIVE_INT, mspace1, filespace );
+      cout << "\n";
+      cout << "Dataset: \n";
+      for (j = 0; j < dims[0]; j++)
+      {
+	 for (i = 0; i < dims[1]; i++)
+	    cout << data_out[j][i] << " ";
+	 cout << endl;
+      }     
+
+      /*
+       *	    dataset rank 2, dimensions 10 x 5 
+       *	    chunk rank 2, dimensions 2 x 5 
+
+       *	    Dataset:
+       *	    1 1 1 3 3 
+       *	    1 1 1 3 3 
+       *	    1 1 1 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       *	    2 0 0 0 0 
+       */
+
+      /*
+       * Read the third column from the dataset.
+       * First define memory dataspace, then define hyperslab
+       * and read it into column array.
+       */
+      hsize_t     col_dims[1];
+      col_dims[0] = 10;
+      DataSpace mspace2( RANKC, col_dims );
+
+      /*
+       * Define the column (hyperslab) to read.
+       */
+      hssize_t offset[2] = { 0, 2 };
+      hsize_t  count[2] = { 10, 1 };
+      int      column[10];        // buffer for column to be read
+
+      filespace.selectHyperslab( H5S_SELECT_SET, count, offset );
+      dataset.read( column, PredType::NATIVE_INT, mspace2, filespace );
+
+      cout << endl;
+      cout << "Third column: " << endl;
+      for (i = 0; i < 10; i++)
+	 cout << column[i] << endl;
+
+      /*
+       *	    Third column: 
+       *	    1 
+       *	    1 
+       *	    1 
+       *	    0 
+       *	    0 
+       *	    0 
+       *	    0 
+       *	    0 
+       *	    0 
+       *	    0 
+       */
+
+      /*
+       * Define the memory space to read a chunk.
+       */
+      DataSpace mspace3( rank_chunk, chunk_dims );
+
+      /*
+       * Define chunk in the file (hyperslab) to read.
+       */
+      offset[0] = 2;
+      offset[1] = 0;
+      count[0]  = chunk_dims[0];
+      count[1]  = chunk_dims[1];
+      filespace.selectHyperslab( H5S_SELECT_SET, count, offset );
+
+      /*
+       * Read chunk back and display.
+       */
+      int chunk_out[2][5];   // buffer for chunk to be read
+      dataset.read( chunk_out, PredType::NATIVE_INT, mspace3, filespace );
+      cout << endl;
+      cout << "Chunk:" << endl;
+      for (j = 0; j < chunk_dims[0]; j++)
+      {
+	 for (i = 0; i < chunk_dims[1]; i++)
+	    cout << chunk_out[j][i] << " ";
+	 cout << endl;
+      }     
+      /*
+       *	 Chunk: 
+       *	 1 1 1 0 0 
+       *	 2 0 0 0 0 
+       */
+   }  // end of try block
+
+   // catch failure caused by the H5File operations
+   catch( FileIException error )
+   {
+      error.printError();
+   }
+
+   // catch failure caused by the DataSet operations
+   catch( DataSetIException error )
+   {
+      error.printError();
+   }
+
+   // catch failure caused by the DataSpace operations
+   catch( DataSpaceIException error )
+   {
+      error.printError();
+   }
+
+   return 0;
+}