NumPy: Where in the source code are `arange` and `array` functions defined?

Question

I was looking for the source code for the arange and array functions in NumPy, but I couldn't find it: https://github.com/numpy/numpy/search?utf8=%E2%9C%93&q=%22def+arange%22+path%3Anumpy%2Fcore&type=

Could anyone enlighten me?

Answer 1

numpy.array and numpy.arange are written in C. You can tell because they say "built-in" when you look at them:

>>> numpy.array
<built-in function array>
>>> numpy.arange
<built-in function arange>

That means there's no def statement. Instead, we look at what module they come from:

>>> numpy.array.__module__
'numpy.core.multiarray'
>>> numpy.arange.__module__
'numpy.core.multiarray'

navigate to the corresponding source file, and take a look at the array controlling the module's exported functions:

{"array",
    (PyCFunction)_array_fromobject,
    METH_VARARGS|METH_KEYWORDS, NULL},
...
{"arange",
    (PyCFunction)array_arange,
    METH_VARARGS|METH_KEYWORDS, NULL},

numpy.array and numpy.arange correspond to _array_fromobject and array_arange in that file. That's not where all the work happens, though. You'll need to keep digging to find all the relevant code.

Answer 2

These are defined in multiarraymodule.c:

https://github.com/numpy/numpy/blob/820765d762513510a8e46f108e8bc8b366127f8f/numpy/core/src/multiarray/multiarraymodule.c#L4279

array function in Python is _array_fromobject() in C, and arange function in Python is array_arange() in C.