'''
    Buffer function like MATLAB. (https://www.mathworks.com/help/signal/ref/buffer.html?searchHighlight=buffer&s_tid=srchtitle)
    
    Ref: https://stackoverflow.com/a/60020929 (Your can see more algorithms)
    About buffer function in Python, see also: https://github.com/aaravindravi/python-signal-segmentation/blob/master/buffer.py
    '''
    if opt not in ('nodelay', None):
        raise ValueError('{} not implemented'.format(opt))

    i = 0
    if opt == 'nodelay':
        # No zeros at array start
        result = x[:n]
        i = n
    else:
        # Start with `p` zeros
        result = np.hstack([np.zeros(p), x[:n-p]])
        i = n-p
    # Make 2D array, cast to list for .append()
    result = list(np.expand_dims(result, axis=0))

    while i < len(x):
        # Create next column, add `p` results from last col if given
        col = x[i:i+(n-p)]
        if p != 0:
            col = np.hstack([result[-1][-p:], col])

        # Append zeros if last row and not length `n`
        if len(col):
            col = np.hstack([col, np.zeros(n - len(col))])

        # Combine result with next row
        result.append(np.array(col))
        i += (n - p)

    return np.vstack(result).T