# Given a set of lines, find only those who are parallel (perspective)

I have an image which includes straight borders which I need to detect: The borders are thick, which causes hough transform to detect multiple lines for each border, as can be seen in the following image:

In order to find the 'true' lines, I want to find all parallel lines (i.e. find the lines which converge into a vanishing point). Does OpenCV (or any other library for the sake of this manner) contains such a functionality? (I'm using python, though I can port c++ scripts as well)

Finally, when multiple lines cause a problem, one could always cluster them using the line parameters $[a,b,c]$. When number of lines are not known, one can use a hierarchical clustering, such as single-linkage or agglomerative clustering.