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# distutils: language = c++
from cpython cimport Py_buffer
from libcpp.vector cimport vector
cdef class Matrix:
cdef Py_ssize_t ncols
cdef Py_ssize_t[2] shape
cdef Py_ssize_t[2] strides
cdef vector[float] v
def __cinit__(self, Py_ssize_t ncols):
self.ncols = ncols
def add_row(self):
"""Adds a row, initially zero-filled."""
self.v.resize(self.v.size() + self.ncols)
def __getbuffer__(self, Py_buffer *buffer, int flags):
cdef Py_ssize_t itemsize = sizeof(self.v[0])
self.shape[0] = self.v.size() // self.ncols
self.shape[1] = self.ncols
# Stride 1 is the distance, in bytes, between two items in a row;
# this is the distance between two adjacent items in the vector.
# Stride 0 is the distance between the first elements of adjacent rows.
self.strides[1] = <Py_ssize_t>( <char *>&(self.v[1])
- <char *>&(self.v[0]))
self.strides[0] = self.ncols * self.strides[1]
buffer.buf = <char *>&(self.v[0])
buffer.format = 'f' # float
buffer.internal = NULL # see References
buffer.itemsize = itemsize
buffer.len = self.v.size() * itemsize # product(shape) * itemsize
buffer.ndim = 2
buffer.obj = self
buffer.readonly = 0
buffer.shape = self.shape
buffer.strides = self.strides
buffer.suboffsets = NULL # for pointer arrays only
def __releasebuffer__(self, Py_buffer *buffer):
pass
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