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A simple tutorial on Arrays
===========================
Let's start with a simple tutorial to create and modify arrays.
Get the necessary headers for numpy components and set up necessary namespaces::
#include <boost/python/numpy.hpp>
#include <iostream>
namespace p = boost::python;
namespace np = boost::python::numpy;
Initialise the Python runtime, and the numpy module. Failure to call these results in segmentation errors::
int main(int argc, char **argv)
{
Py_Initialize();
np::initialize();
Zero filled n-dimensional arrays can be created using the shape and data-type of the array as a parameter. Here, the shape is 3x3 and the datatype is the built-in float type::
p::tuple shape = p::make_tuple(3, 3);
np::dtype dtype = np::dtype::get_builtin<float>();
np::ndarray a = np::zeros(shape, dtype);
You can also create an empty array like this ::
np::ndarray b = np::empty(shape,dtype);
Print the original and reshaped array. The array a which is a list is first converted to a string, and each value in the list is extracted using extract< >::
std::cout << "Original array:\n" << p::extract<char const *>(p::str(a)) << std::endl;
// Reshape the array into a 1D array
a = a.reshape(p::make_tuple(9));
// Print it again.
std::cout << "Reshaped array:\n" << p::extract<char const *>(p::str(a)) << std::endl;
}
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