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48 lines
1.5 KiB
ReStructuredText
48 lines
1.5 KiB
ReStructuredText
.. highlight:: c
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h5::array_proxy : a simple proxy to the array in file
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===========================================================
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The principle is that `array_proxy` is a proxy to an array, possibly big, in the h5 file.
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It has a domain, and can be assigned from/to an array and sliced.
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This allows to read/write only parts of a large array using the same slicing syntax
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as for the array class itself (which is then translated into the hyperslab technique of the HDF5 library).
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Tutorial
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-----------
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* Write a "big" array in the h5 file and write it slice by slice::
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#include <triqs/arrays/h5/array_proxy.hpp>
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using namespace triqs::arrays;
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h5::H5File file( "ess.h5", H5F_ACC_TRUNC );
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// first create a 'big' array in the file (no temporary is made in memory, it uses directly the HDF5 API).
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const size_t N = 100;
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h5::array_proxy<T,3,3> Pn( file, "Z", make_shape(N,2,2) );
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// a slice...
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array<double,2> the_slice (2,2); the_slice() = 1;
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// write the large array slice by slice
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for (int u = 0; u<N; ++u) P (u,range(), range()) = u* the_slice; // or any array expression
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* Read a "big" array slice by slice::
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#include <triqs/arrays/h5/array_proxy.hpp>
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using namespace triqs::arrays;
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h5::H5File file ("ess.h5", H5F_ACC_RDONLY );
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h5::array_proxy<T,3,3> P(file, "A");
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array<T,2> a_slice ;
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for (int u = 0; u<N; ++u) a_slice = P (u,range(), range()) ;
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Reference
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------------
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You can also get the :doxy:`full C++ documentation<triqs::arrays::h5::array_proxy>` for this class.
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