a simple mat class which mimic the behavior of Eigen.

eigen_style_mat.py

from dataclasses import dataclass
from typing import Any, Optional, Sequence


@dataclass
class Mat:
    row: int
    col: int
    data: Optional[Sequence[Sequence[Any]]] = None

    def __lshift__(self, other: Sequence):
        if not isinstance(other, Sequence):
            raise TypeError("other must be a sequence")
        if len(other) != self.col * self.row:
            raise ValueError("Number of elements does not match")
        self.data = [
            other[i : i + self.col]
            for i in range(0, self.col * self.row, self.col)
        ]

    def __str__(self) -> str:
        return str(self.data)


m = Mat(4, 5)
# fmt: off
m << (
1, 2, 3, 4, 5, #
6, 7, 8, 9, 10, #
11, 12, 13, 14, 15,# 
16, 17, 18, 19, 20)
# fmt: on
n = Mat(4, 5)
# fmt: off
n << [
1, 2, 3, 4, 5, #
6, 7, 8, 9, 10, #
11, 12, 13, 14, 15,# 
16, 17, 18, 19, 20]
# fmt: on
print(m, n)