用Python和OpenCV实现零除法

Question

我使用此代码从下图中删除行：

我不知道原因，但它给出了第34行x0, x1, y0, y1 = (0, im_wb.shape[1], sum(y0_list)/len(y0_list), sum(y1_list)/len(y1_list))的输出ZeroDivisionError: division by zero error。在

原因是什么？我怎样才能修好它？在

import cv2
import numpy as np

img = cv2.imread('lines.png',0)

# Applies threshold and inverts the image colors
(thresh, im_bw) = cv2.threshold(img, 128, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
im_wb = (255-im_bw)

# Line parameters
minLineLength = 100
maxLineGap = 10
color = 255
size = 1

# Substracts the black line
lines = cv2.HoughLinesP(im_wb,1,np.pi/180,minLineLength,maxLineGap)[0]

# Makes a list of the y's located at position x0 and x1
y0_list = []
y1_list = []
for x0,y0,x1,y1 in lines:
    if x0 == 0:
        y0_list.append(y0)
    if x1 == im_wb.shape[1]:
        y1_list.append(y1)

# Calculates line thickness and its half
thick = max(len(y0_list), len(y1_list))
hthick = int(thick/2)

# Initial and ending point of the full line
x0, x1, y0, y1 = (0, im_wb.shape[1], sum(y0_list)/len(y0_list), sum(y1_list)/len(y1_list))

# Iterates all x's and prints makes a vertical line with the desired thickness
# when the point is surrounded by white pixels
for x in range(x1):
    y = int(x*(y1-y0)/x1) + y0
    if im_wb[y+hthick+1, x] == 0 and im_wb[y-hthick-1, x] == 0:
        cv2.line(img,(x,y-hthick),(x,y+hthick),colour,size)

cv2.imshow('clean', img)
cv2.waitKey(0)

这个问题涉及另一个问题：Python: How to OCR characters crossed by a horizontal line

Answer 1

错误的原因是长度是y0_list或{}（或两者都是）的0。因为在for循环中初始化了它们：

for x0,y0,x1,y1 in lines:
    if x0 == 0:
        y0_list.append(y0)
    if x1 == im_wb.shape[1]:
        y1_list.append(y1)

您可以将错误缩小到lines没有预期值，或者您的2if语句有错误。我相信问题是由后者引起的，但最简单的检查方法是打印出lines，并手动检查if语句是否会被触发。在