Independently roll rows of a tensor.

indep_roll.py

# Copied from https://stackoverflow.com/a/56175538/955952

def indep_roll(arr, shifts, axis=1):
    """Apply an independent roll for each dimensions of a single axis.

    Parameters
    ----------
    arr : np.ndarray
        Array of any shape.

    shifts : np.ndarray
        How many shifting to use for each dimension. Shape: `(arr.shape[axis],)`.

    axis : int
        Axis along which elements are shifted. 
    """
    arr = np.swapaxes(arr,axis,-1)
    all_idcs = np.ogrid[[slice(0,n) for n in arr.shape]]

    # Convert to a positive shift
    shifts[shifts < 0] += arr.shape[-1] 
    all_idcs[-1] = all_idcs[-1] - shifts[:, np.newaxis]

    result = arr[tuple(all_idcs)]
    arr = np.swapaxes(result,-1,axis)
    return arr