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October 2016

4 participants
2 discussions

Boost.Python NumPy extension
by Stefan Seefeld Oct. 9, 2016

Oct. 9, 2016

Hello, I'm happy to announce that I just merged the NumPy C++ wrappers from https://github.com/ndarray/Boost.NumPy into Boost.Python's development branch. (Online documentation for it can be browsed here: http://boostorg.github.io/python/develop/doc/html/numpy) I'd very much like to be able to merge this into the master branch for the next Boost release (version 1.63). At present I'm using SCons to build Boost.Python (stand-alone, against a separately installed Boost), which is also the infrastructure I use for CI testing (https://travis-ci.org/boostorg/python). I would like to ask for help with integrating the new NumPy extension into the Boost.Build-based build system, such that this will also be picked up by the regular Boost infrastructure. Please refer to https://github.com/boostorg/python/issues/89 if you'd like to help with this. Many thanks ! Stefan -- ...ich hab' noch einen Koffer in Berlin...

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Boost Python. access pandas columns in the same order as in python
by Vladimir Sakharuk Oct. 5, 2016

Oct. 5, 2016

Hello All, Trying to figure out how to c++ access pandas dataframe columns in the same order as they exist in the python. in python: import pandas df = pandas.DataFrame.from_items([('CCC', [5]), ('BBB', [1]), ('AAA', [4])]) df.columns # outputs Index([u'CCC', u'BBB', u'AAA'], dtype='object') in C++ when passing df to foo. foo(const boost::python::object in_obj) { boost::python::stl_input_iterator<boost::python::object> it (in_obj), end; int index=0; for(; it != end; it++) { auto extracted = boost::python::extract<char const *> (*it); char const * colname = extracted; std::cout<<"index="<<index<<", colname="<<colname<<std::endl; index++; } } //outputs regardless of original order of column names. //index=0, colname=AAA //index=1, colname=BBB //index=2, colname=CCC As you can see pythons' order 'CCC','BBB','AAA' is not same as c++ 'AAA', 'BBB', 'CCC'. Looks like those order depend on object hasing. How could I get those values in the original order of pandas dataframe from C++? Thank you.

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