python 如何计算差分

▽ x t \triangledown x_t ▽xt为 x t x_t xt的1阶差分： ▽ x t = x t ? x t ? 1 \triangledown x_t=x_t-x_{t-1} ▽xt=xt?xt?1 ▽ 2 x t \triangledown^2 x_t ▽2xt​ 为 x t x_t xt​的2阶差分： ▽ x t = ▽ x t − ▽ x t − 1 \triangledown x_t=\triangledown x_t-\triangledown x_{t-1} ▽xt​=▽xt​−▽xt−1​ ▽ p x t \triangledown^p x_t ▽pxt​为 x t x_t xt​的p阶差分： ▽ x t = ▽ p − 1 x t − ▽ p − 1 x t − 1 \triangledown x_t=\triangledown^{p-1} x_t-\triangledown^{p-1} x_{t-1} ▽xt​=▽p−1xt​−▽p−1xt−1​

▽ k x t \triangledown_k x_t ▽k​xt​为 x t x_t xt​的1阶差分： ▽ k x t = x t − x t − k \triangledown_k x_t=x_t-x_{t-k} ▽k​xt​=xt​−xt−k​

diff_p = diff(data, n=p)

diff_k_step = data.diff(k)