the potential solution to the failing case for the yellow lane video in Project 1

[animebing]

Thank you for sharing the code and the detailed description of your code. In Shortcomings of your writeup, you said that there are some failing cases in the yellow lane video, I write my code based on yours and encounter the same issue, today I find the potential reason of the issue. The reason may be that there are some horizontal line segments after Hough Transform and I have verified that these horizontal line segments can't be filtered in function draw_lines and find_line_fit.

In function draw_lines, in the first for line in lines loop, I add following code to filter these line segments
if np.abs(slope) < 0.09:
continue

because tan(5) = 0.087, here is degree, not radian, so I use 0.09 to filter these line segments with degree less than 5, maybe you can have a try to see whether it works