Intended Function of code: Takes a user input for the volume of 3 jars(1-9) and output the volumes with one of the jars containing the target length. jars can be Emptied/Filled a jar, or poured from one jar to another until one is empty or full. With the code I have, i'm stuck on a key exception error . Target length is 4 for this case
Code:
`
class Graph:
class GraphNode:
def __init__(self, jar1 = 0, jar2 = 0, jar3 = 0, color = "white", pi = None):
self.jar1 = jar1
self.jar2 = jar2
self.jar3 = jar3
self.color = color
self.pi = pi
def __repr__(self):
return str(self)
def __init__(self, jl1 = 0, jl2 = 0, jl3 = 0, target = 0):
self.jl1 = jl1
self.jl2 = jl2
self.jl3 = jl3
self.target = target
self.V = {}
for x in range(jl1 + 1):
for y in range(jl2 + 1):
for z in range(jl3 + 1):
node = Graph.GraphNode(x, y, z, "white", None)
self.V[node] = None
def isFound(self, a: GraphNode) -> bool:
if self.target in [a.jar1, a.jar2, a.jar3]:
return True
return False
pass
def isAdjacent(self, a: GraphNode, b: GraphNode) -> bool:
if self.V[a]==b:
return True
return False
pass
def BFS(self) -> [] :
start = Graph.GraphNode(0, 0, 0, "white")
queue=[]
queue.append(start)
while len(queue)>0:
u=queue.pop(0)
for v in self.V:
if self.isAdjacent(u,v):
if v.color =="white":
v.color == "gray"
v.pi=u
if self.isFound(v):
output=[]
while v.pi is not None:
output.insert(0,v)
v=v.pi
return output
else:
queue.append(v)
u.color="black"
return []
#######################################################
j1 = input("Size of first jar: ")
j2 = input("Size of second jar: ")
j3 = input("Size of third jar: ")
t = input("Size of target: ")
jar1 = int(j1)
jar2 = int(j2)
jar3 = int(j3)
target = int(t)
graph1 = Graph(jar1, jar2, jar3, target)
output = graph1.BFS()
print(output)
` **Error: **
line 37, in isAdjacent
if self.V[a]==b:
KeyError: <exception str() failed>
Strange but when I first ran this in the IPython interpreter I got a different exception:
... :35, in Graph.isAdjacent(self, a, b)
34 def isAdjacent(self, a: GraphNode, b: GraphNode) -> bool:
---> 35 if self.V[a]==b:
36 return True
37 return False
<class 'str'>: (<class 'RecursionError'>, RecursionError('maximum recursion depth exceeded while getting the str of an object'))
When I run it as a script or in the normal interpreter I do get the same one you had:
... line 35, in isAdjacent
if self.V[a]==b:
KeyError: <exception str() failed>
I'm not sure what this means so I ran the debugger and got this:
File "/Users/.../stackoverflow/bfs1.py", line 1, in <module>
class Graph:
File "/Users/.../stackoverflow/bfs1.py", line 47, in BFS
if self.isAdjacent(u,v):
File "/Users/.../stackoverflow/bfs1.py", line 35, in isAdjacent
if self.V[a]==b:
KeyError: <unprintable KeyError object>
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /Users/.../stackoverflow/bfs1.py(35)isAdjacent()
-> if self.V[a]==b:
(Pdb) type(a)
<class '__main__.Graph.GraphNode'>
(Pdb) str(a)
*** RecursionError: maximum recursion depth exceeded while calling a Python object
So it does seem like a maximum recursion error. (The error message you originally got is not very helpful). But the words <unprintable KeyError object> are a clue. It looks like it was not able to display the KeyError exception...
The culprit is this line in your class definition:
def __repr__(self):
return str(self)
What were you trying to do here?
The __repr__ function is called when the class is asked to produce a string representation of itself. But yours calls the string function on the instance of the class so it will call itself! So I think you actually generated a second exception while the debugger was trying to display the first!!!.
I replaced these lines with
def __repr__(self):
return f"GraphNode({self.jar1}, {self.jar2}, {self.jar3}, {self.color}, {self.pi})"
and I don't get the exception now:
Size of first jar: 1
Size of second jar: 3
Size of third jar: 6
Size of target: 4
Traceback (most recent call last):
File "/Users/.../stackoverflow/bfs1.py", line 77, in <module>
output = graph1.BFS()
File "/Users/.../stackoverflow/bfs1.py", line 45, in BFS
if self.isAdjacent(u,v):
File "/Users/.../stackoverflow/bfs1.py", line 33, in isAdjacent
if self.V[a]==b:
KeyError: GraphNode(0, 0, 0, white, None)
This exception is easier to interpret. Now it's over to you to figure out why this GraphNode was not found in the keys of self.V!