使用Python和OpenCV获得零错误除法

Question

我正在使用此代码删除以下图片中的行：

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

原因是什么？我该如何解决？

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)

问题的另一个问题是：Python: How to OCR characters crossed by a horizontal line

Answer 1

错误的原因是y0_list或y1_list（或两者）的长度为0。因为你在这个for循环中初始化它们：

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

您可以将错误范围缩小到lines没有预期值或2 if语句错误。我认为问题是由后者引起的，但您可以执行的最简单的检查是打印lines并手动检查是否会触发if语句。