Issue with nested loops in Ruby - ruby

Question

So I right now I have a list of edges of a graph. With this list, I'm trying to build a adjacency map, in which its key is an edge and the value is a list of edges that are adjacent to the edge. I'm using a nested loop that compares each edge in the list to every other edge in the list. However, this is not building a map that I expect it to. Below is my code:
def build_adjacency
#paths.each do |start_path|
#paths.each do |end_path|
# 3 cases for edge adcency
if (start_path.end_node == end_path.start_node) || (start_path.start_node == end_path.end_node) || (start_path.start_node == end_path.start_node)
if #adjacency_map.has_key?("#{start_path}".to_s)
#adjacency_map[:"#{start_path}".to_s] << end_path
else
value = [end_path]
#adjacency_map[:"#{start_path}".to_s] = value
end
end
end
end
end
I also tried array.combination but that is not working either. Thank you for the help.
Test input: (start node, end node, color, type)
A B R C
B E B C
B C B T
C D G T
Output for #adjacency_map:
C:\Users\Jin\Documents\Mines\Algorithms (CSCI 406)\Project_3>ruby graph.rb
Key: A B R C Value: [#<Path:0x2548a28 #start_node="A", #end_node="B", #color=
"R", #type="C">, #<Path:0x2548968 #start_node="B", #end_node="E", #color="B", #t
ype="C">, #<Path:0x25488a8 #start_node="B", #end_node="C", #color="B", #type="T"
>, #<Path:0x25487e8 #start_node="C", #end_node="D", #color="G", #type="T">]
Key: B E B C Value: [#<Path:0x2548a28 #start_node="A", #end_node="B", #color=
"R", #type="C">, #<Path:0x2548968 #start_node="B", #end_node="E", #color="B", #t
ype="C">, #<Path:0x25488a8 #start_node="B", #end_node="C", #color="B", #type="T"
>, #<Path:0x25487e8 #start_node="C", #end_node="D", #color="G", #type="T">]
Key: B C B T Value: [#<Path:0x2548a28 #start_node="A", #end_node="B", #color=
"R", #type="C">, #<Path:0x2548968 #start_node="B", #end_node="E", #color="B", #t
ype="C">, #<Path:0x25488a8 #start_node="B", #end_node="C", #color="B", #type="T"
>, #<Path:0x25487e8 #start_node="C", #end_node="D", #color="G", #type="T">]
Key: C D G T Value: [#<Path:0x2548a28 #start_node="A", #end_node="B", #color=
"R", #type="C">, #<Path:0x2548968 #start_node="B", #end_node="E", #color="B", #t
ype="C">, #<Path:0x25488a8 #start_node="B", #end_node="C", #color="B", #type="T"
>, #<Path:0x25487e8 #start_node="C", #end_node="D", #color="G", #type="T">]

Answer 1

The following is strange:
:"#{start_path}".to_s
What ever class your object start_path is, you convert it to a string via interpolation, than convert it to a symbol, only to then convert it to a string again. You can just use strings as hash keys. And in your call to has_key? you have not used the colon. (should normally make no difference)
Also, if you unsure about you implemented the condition correctly, I recommend to create a method to encapsulate it. Especially when the condition has a semantic meaning.

Answer 2

It seems that only problem with your code that it's not checking if start_path and end_path are the same. So, it adds unnecessary "A-B is adjacent to A-B" into your map.
Maybe you should try just add one line?
def build_adjacency
#paths.each do |start_path|
#paths.each do |end_path|
next if start_path == end_path # this one!
# 3 cases for edge adcency
if (start_path.end_node == end_path.start_node) || (start_path.start_node == end_path.end_node) || (start_path.start_node == end_path.start_node)
if #adjacency_map.has_key?("#{start_path}".to_s)
#adjacency_map[:"#{start_path}".to_s] << end_path
else
value = [end_path]
#adjacency_map[:"#{start_path}".to_s] = value
end
end
end
end
end
Here's my full code, reproducing the solution: https://gist.github.com/zverok/6785c213fd78430cd423