def read_mtx(filename: PathLike, dtype: str='float32') -> AnnData:
    """Read ``.mtx`` file.

    Parameters
    ----------
    filename
        The filename.
    dtype
        Numpy data type.
    """
    from scipy.io import mmread
    # could be rewritten accounting for dtype to be more performant
    X = mmread(fspath(filename)).astype(dtype)
    from scipy.sparse import csr_matrix
    X = csr_matrix(X)
    return AnnData(X, dtype=dtype)
Read ``.mtx`` file.

    Parameters
    ----------
    filename
        The filename.
    dtype
        Numpy data type.