def resample(x, t, start, end, step):
    bins = np.arange(start, end+step, step)
    inds = np.digitize(t,bins)
    y = np.empty(len(bins)) * np.nan
    y[inds] = x
    return y, bins

x = [3,6,9,12,15,18,21,24]
t = [0,4,8,10,45,67,78,90]
x_re, t_re = resample(x, t, 0, 100, 5)