写出用图片识别横向坡度的算法代码

以下是一个用Python实现的基于OpenCV库的图片识别横向坡度的算法代码：

import cv2
import numpy as np

# 读取图片
img = cv2.imread('test.jpg')

# 图片预处理
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5, 5), 0)
edges = cv2.Canny(blur, 50, 150, apertureSize=3)

# 直线检测
lines = cv2.HoughLines(edges, 1, np.pi/180, 200)

# 计算坡度
sum_theta = 0
count_theta = 0

for line in lines:
    rho, theta = line[0]
    a = np.cos(theta)
    b = np.sin(theta)
    x0 = a*rho
    y0 = b*rho
    x1 = int(x0 + 1000*(-b))
    y1 = int(y0 + 1000*a)
    x2 = int(x0 - 1000*(-b))
    y2 = int(y0 - 1000*a)
    cv2.line(img, (x1, y1), (x2, y2), (0, 0, 255), 2)

    if abs(theta - np.pi/2) < np.pi/6: # 过滤掉斜率较大的直线
        sum_theta += theta
        count_theta += 1

if count_theta > 0:
    avg_theta = sum_theta / count_theta
    slope = np.tan(avg_theta) # 计算横向坡度
    print('横向坡度为：', slope)

# 显示结果
cv2.imshow('img', img)
cv2.waitKey(0)
cv2.destroyAllWindows()

注意，该代码仅供参考，具体实现需要根据实际情况进行调整和优化。