Port of embed to python

embed.py

import numpy as np

def embed(x,y, dimension):
    """
    embed 2 vectors
    >>> embed([1,2,3], [4,5,6], 2)
    array([[ 2.,  5.,  1.,  4.],
           [ 3.,  6.,  2.,  5.]])
    >>> embed([1,2,3], [4,5,6], 3)
    array([[ 3.,  6.,  2.,  5.,  1.,  4.]])
    >>> embed([1,2,3,4,5], [4,5,6,7,8], 2)
    array([[ 2.,  5.,  1.,  4.],
           [ 3.,  6.,  2.,  5.],
           [ 4.,  7.,  3.,  6.],
           [ 5.,  8.,  4.,  7.]])
    """
    assert len(x) == len(y), "both vectors x and y should have same length"
    n = len(x)
    m = 2
    matrix = np.zeros((n - dimension + 1, dimension * 2))
    for row in range(matrix.shape[0]):
        for col in range(dimension):
            matrix[row, (col * 2)]     = x[row + (dimension - col) - 1]
            matrix[row, (col * 2) + 1] = y[row + (dimension - col) - 1]
    return matrix
     

if __name__ == '__main__':
     import sys, doctest
     sys.exit(doctest.testmod()[0])

foo.R

> embed(c(1, 2, 3), 2)                                                                                                                                         
     [,1] [,2]
[1,]    2    1
[2,]    3    2
> embed(c(1, 2, 3, 4), 2)
     [,1] [,2]
[1,]    2    1
[2,]    3    2
[3,]    4    3