帮我写一个计算单个像素梯度的代码

以下是一个计算单个像素梯度的Python代码示例：

import numpy as np

def calculate_gradient(pixel, image):
    """
    Calculate the gradient of a single pixel in an image.

    Parameters:
    pixel (tuple): The (x, y) coordinates of the pixel to calculate the gradient for.
    image (numpy.ndarray): The image to calculate the gradient in.

    Returns:
    tuple: A tuple containing the x-gradient and y-gradient of the pixel.
    """
    x, y = pixel
    rows, cols = image.shape

    # Calculate x-gradient
    if x == 0:
        dx = image[x+1, y] - image[x, y]
    elif x == rows-1:
        dx = image[x, y] - image[x-1, y]
    else:
        dx = (image[x+1, y] - image[x-1, y]) / 2

    # Calculate y-gradient
    if y == 0:
        dy = image[x, y+1] - image[x, y]
    elif y == cols-1:
        dy = image[x, y] - image[x, y-1]
    else:
        dy = (image[x, y+1] - image[x, y-1]) / 2

    return dx, dy

该函数接收两个参数：要计算梯度的像素坐标和图像数组。函数首先确定指定像素的位置，然后计算该像素的x和y梯度。如果像素位于图像边缘，则只使用相邻像素计算梯度。最后，函数将两个梯度值作为元组返回。