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Benno Evers
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Update documentation after introducing numpy
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‎Makefile‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,11 @@
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examples: minimal basic modern
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minimal: examples/minimal.cpp matplotlibcpp.h
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cd examples && g++ minimal.cpp -lpython2.7 -o minimal -std=c++11
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cd examples && g++ -DWITHOUT_NUMPY minimal.cpp -I/usr/include/python2.7 -lpython2.7 -o minimal -std=c++11
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basic: examples/basic.cpp matplotlibcpp.h
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cd examples && g++ basic.cpp -lpython2.7 -o basic
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cd examples && g++ basic.cpp -I/usr/include/python2.7 -lpython2.7 -o basic
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modern: examples/modern.cpp matplotlibcpp.h
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cd examples && g++ modern.cpp -lpython2.7 -o modern -std=c++11
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cd examples && g++ modern.cpp -I/usr/include/python2.7 -lpython2.7 -o modern -std=c++11
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‎README.md‎

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@@ -17,7 +17,7 @@ Complete minimal example:
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plt::show();
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}
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// g++ minimal.cpp -std=c++11 -lpython2.7
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// g++ minimal.cpp -std=c++11 -I/usr/include/python2.7 -lpython2.7
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Result: ![Minimal example](./examples/minimal.png)
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@@ -54,7 +54,7 @@ A more comprehensive example:
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plt::save("./basic.png");
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}
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// g++ basic.cpp -lpython2.7
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// g++ basic.cpp -I/usr/include/python2.7 -lpython2.7
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Result: ![Basic example](./examples/basic.png)
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@@ -87,37 +87,39 @@ matplotlib-cpp doesn't require C++11, but will enable some additional syntactic
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plt::show();
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}
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// g++ modern.cpp -std=c++11 -lpython
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// g++ modern.cpp -std=c++11 -I/usr/include/python2.7 -lpython
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Result: ![Modern example](./examples/modern.png)
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Installation
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------------
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matplotlib-cpp works by wrapping the popular python plotting library matplotlib. (matplotlib.org)
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This means you have to have a working python installation, including development headers.
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On Ubuntu:
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sudo aptitude install python-matplotlib python2.7-dev
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sudo aptitude install python-matplotlib python-numpy python2.7-dev
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If, for some reason, you're unable to get a working installation of numpy on your system,
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you can add the define `WITHOUT_NUMPY` to erase this dependency.
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The C++-part of the library consists of the single header file `matplotlibcpp.h` which can be placed
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anywhere.
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Since a python interpreter is opened internally, it is necessary to link against `libpython2.7` in order to use
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matplotlib-cpp.
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# Python 3
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The code is written in a way that should support both python2 and python3.
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By default, matplotlib-cpp will try to "just work" and include the header `python2.7/Python.h`.
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This library supports both python2 and python3 (although the python3 support is probably far less tested,
115+
so it is recommended to prefer python2.7). To switch the used python version, simply change
116+
the compiler flags accordingly.
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To modify this behaviour the define `MATPLOTLIBCPP_PYTHON_HEADER`,
113-
can be set to an absolute or relative path:
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g++ example.cpp -I/usr/include/python3.6 -lpython3.6
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#define MATPLOTLIBCPP_PYTHON_HEADER /usr/include/python3.6/Python.h
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#include "matplotlibcpp.h"
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The same technique can be used for linking against a custom build of python
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or
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g++ -DMATPLOTLIBCPP_PYTHON_HEADER=Python.h -I/usr/include/python3.6 <...>
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g++ example.cpp -I/usr/local/include/fancy-python4 -L/usr/local/lib -lfancy-python4
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Why?
@@ -152,7 +154,5 @@ Todo/Issues/Wishlist
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* Right now, only a small subset of matplotlibs functionality is exposed. Stuff like xlabel()/ylabel() etc. should
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be easy to add.
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* A lot of copying could be avoided if we generate numpy arrays directly instead of python lists
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* If you use Anaconda on Windows, you might need to set PYTHONHOME to Anaconda home directory and QT_QPA_PLATFORM_PLUGIN_PATH to %PYTHONHOME%Library/plugins/platforms. The latter is for especially when you get the error which says 'This application failed to start because it could not find or load the Qt platform plugin "windows"
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in "".'

‎examples/minimal.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,6 @@
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namespace plt = matplotlibcpp;
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int main() {
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plt::plot({1,2,3,4});
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plt::plot({1,3,2,4});
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plt::show();
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}

‎matplotlibcpp.h‎

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Original file line numberDiff line numberDiff line change
@@ -6,26 +6,23 @@
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#include <algorithm>
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#include <stdexcept>
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#include <iostream>
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#include <stdint.h> // <cstdint> requires c++11 support
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#if __cplusplus > 199711L || _MSC_VER > 1800
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#include <functional>
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#endif
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// i.e. g++ -DMATPLOTLIBCPP_PYTHON_HEADER=/usr/include/python3.6/Python.h [...]
15-
#ifdef MATPLOTLIBCPP_PYTHON_HEADER
16-
#define STRINGIFY_(x) #x
17-
#define STRINGIFY(x) STRINGIFY_(x)
18-
#include STRINGIFY(MATPLOTLIBCPP_PYTHON_HEADER)
19-
#else // This should stay the default for backwards compatibility
20-
#include <python2.7/Python.h>
21-
#endif
15+
#include <Python.h>
16+
17+
#ifndef WITHOUT_NUMPY
18+
#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
19+
#include <numpy/arrayobject.h>
20+
#endif // WITHOUT_NUMPY
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#if PY_MAJOR_VERSION >= 3
2423
#define PyString_FromString PyUnicode_FromString
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#endif
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27-
#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
28-
#include <numpy/arrayobject.h>
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namespace matplotlibcpp {
3128

@@ -68,14 +65,16 @@ namespace matplotlibcpp {
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// optional but recommended
7067
#if PY_MAJOR_VERSION >= 3
71-
wchar_t name[] = L"plotting";
68+
wchar_t name[] = L"plotting";
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#else
73-
char name[] = "plotting";
70+
char name[] = "plotting";
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#endif
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Py_SetProgramName(name);
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Py_Initialize();
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75+
#ifndef WITHOUT_NUMPY
7876
import_array(); // initialize numpy C-API
77+
#endif
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PyObject* pyplotname = PyString_FromString("matplotlib.pyplot");
8180
PyObject* pylabname = PyString_FromString("pylab");
@@ -182,19 +181,21 @@ namespace matplotlibcpp {
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183182
return res;
184183
}
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185+
#ifndef WITHOUT_NUMPY
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// Type selector for numpy array conversion
186187
template <typename T> struct select_npy_type { const static NPY_TYPES type = NPY_NOTYPE; }; //Default
187188
template <> struct select_npy_type<double> { const static NPY_TYPES type = NPY_DOUBLE; };
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template <> struct select_npy_type<float> { const static NPY_TYPES type = NPY_FLOAT; };
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template <> struct select_npy_type<bool> { const static NPY_TYPES type = NPY_BOOL; };
190-
template <> struct select_npy_type<std::int8_t> { const static NPY_TYPES type = NPY_INT8; };
191-
template <> struct select_npy_type<std::int16_t> { const static NPY_TYPES type = NPY_SHORT; };
192-
template <> struct select_npy_type<std::int32_t> { const static NPY_TYPES type = NPY_INT; };
193-
template <> struct select_npy_type<std::int64_t> { const static NPY_TYPES type = NPY_INT64; };
194-
template <> struct select_npy_type<std::uint8_t> { const static NPY_TYPES type = NPY_UINT8; };
195-
template <> struct select_npy_type<std::uint16_t> { const static NPY_TYPES type = NPY_USHORT; };
196-
template <> struct select_npy_type<std::uint32_t> { const static NPY_TYPES type = NPY_ULONG; };
197-
template <> struct select_npy_type<std::uint64_t> { const static NPY_TYPES type = NPY_UINT64; };
191+
template <> struct select_npy_type<int8_t> { const static NPY_TYPES type = NPY_INT8; };
192+
template <> struct select_npy_type<int16_t> { const static NPY_TYPES type = NPY_SHORT; };
193+
template <> struct select_npy_type<int32_t> { const static NPY_TYPES type = NPY_INT; };
194+
template <> struct select_npy_type<int64_t> { const static NPY_TYPES type = NPY_INT64; };
195+
template <> struct select_npy_type<uint8_t> { const static NPY_TYPES type = NPY_UINT8; };
196+
template <> struct select_npy_type<uint16_t> { const static NPY_TYPES type = NPY_USHORT; };
197+
template <> struct select_npy_type<uint32_t> { const static NPY_TYPES type = NPY_ULONG; };
198+
template <> struct select_npy_type<uint64_t> { const static NPY_TYPES type = NPY_UINT64; };
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199200
template<typename Numeric>
200201
PyObject* get_array(const std::vector<Numeric>& v)
@@ -203,18 +204,32 @@ namespace matplotlibcpp {
203204
NPY_TYPES type = select_npy_type<Numeric>::type;
204205
if (type == NPY_NOTYPE)
205206
{
206-
std::vector<double> vd(v.size());
207-
npy_intp vsize = v.size();
208-
std::copy(v.begin(),v.end(),vd.begin());
209-
PyObject* varray = PyArray_SimpleNewFromData(1, &vsize, NPY_DOUBLE, (void*)(vd.data()));
210-
return varray;
207+
std::vector<double> vd(v.size());
208+
npy_intp vsize = v.size();
209+
std::copy(v.begin(),v.end(),vd.begin());
210+
PyObject* varray = PyArray_SimpleNewFromData(1, &vsize, NPY_DOUBLE, (void*)(vd.data()));
211+
return varray;
211212
}
212213

213214
npy_intp vsize = v.size();
214215
PyObject* varray = PyArray_SimpleNewFromData(1, &vsize, type, (void*)(v.data()));
215216
return varray;
216217
}
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219+
#else // fallback if we don't have numpy: copy every element of the given vector
220+
221+
template<typename Numeric>
222+
PyObject* get_array(const std::vector<Numeric>& v)
223+
{
224+
PyObject* list = PyList_New(v.size());
225+
for(size_t i = 0; i < v.size(); ++i) {
226+
PyList_SetItem(list, i, PyFloat_FromDouble(v.at(i)));
227+
}
228+
return list;
229+
}
230+
231+
#endif // WITHOUT_NUMPY
232+
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template<typename Numeric>
219234
bool plot(const std::vector<Numeric> &x, const std::vector<Numeric> &y, const std::map<std::string, std::string>& keywords)
220235
{

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