def flds_sort(d,s):
    '''
    Sort based on position. Sort with s as a tuple of the sort
    indices and shape from first sort.
    Parameters:
    -----------
    d   -- the flds/sclr data
    s   -- (si, shape) sorting and shaping data from firstsort.
    '''
    labels = [ key for key in d.keys()
               if key not in ['t', 'xs', 'ys', 'zs', 'fd', 'sd'] ];
    si,shape = s;
    for l in labels:
        d[l] = d[l][si].reshape(shape);
        d[l] = np.squeeze(d[l]);
    return d;