Use numpy arrays instead of python lists

[ChristosT]

Swapping python lists for numpy arrays removes the need of copying the data.

[lava]

Hi, thanks for the PR, I've been hoping someone would pick up this task eventually :)

However, it seems like you're currently hard-coding arrays of type NPY_DOUBLE, which would probably break if e.g. a vector<int> gets plotted?

[ChristosT]

@lava yes you are right I missed that one ! I thought that double was enough because you were also converting them with PyFloat_FromDouble(x.at(i))) but PyArray_SimpleNewFromData may still break !

What about a templated type selector like this : http://stackoverflow.com/a/35061296
What do you think ? Do you have a better suggestion on how to handle this ?

[lava]

Yes, that looks like a good solution. Also, to prevent people from seeing some long and weird template error, I'd suggest adding a default case which will internally create a vector of doubles from the input data if the type is not recognized by the selector.

[ChristosT]

This should do it

[lava]

It looks good, but there is one more issue - numpy includes <Python.h>, which requires setting up the include path consistently with the include of <python2.7/Python.h> in matplotlibcpp.h.

Switching to numpy seems like a big enough gain that I'll probably just switch to Python.h in the main header file (or feel free do update the pull request doing it yourself), but I'll probably wait a few days to see if I can think of a solution to avoid this.

[lava]

Merged, thanks for the contribution!