I am having problems executing the __str__ method as it gives me an error. It pr
ID: 3742216 • Letter: I
Question
I am having problems executing the __str__ method as it gives me an error. It prints my message but gives me an error, I tried replacing print with a return but then it wouldn't print my message. Is there any way to fix this? I have attached my entire code below if that helps with any questions you have about it.
class Diset(object):
"""A disjoint-set data structure is a collection of disjoint dynamic sets"""
# Diset supports Makeset, Findset, Addtoset, and Union methods
def __init__(self):
"""Create an empty dictionary to store keys and values"""
self.dset = {}
def Makeset(self, rep):
"""Creates a key-value pair with rep being the key to an empty set which represents the potential values"""
#If rep is a number, processes number regularly
try:
int(rep)
# If the rep is cointained in dictionary's list of keys, error message is produced
if rep in self.dset.keys():
print("There is already a set with representative" + str(rep))
# If not creates a key-value pair with rep being the key and an empty list to cointain values
else:
self.dset.setdefault(rep, [])
# If rep is not a number, does not process and prints error message
except ValueError:
print(str(rep) + " is not a number, try again")
def Addtoset(self,rep,num):
"""Adds a value to the empty set of the matching key represented by rep"""
#If rep is a number, processes number regularly
try:
n = int(num)
# If repkey is in the dictionary decision path is created
if rep in self.dset.keys():
# If the num alue is already in the repkey values list, prints error message
if num in [x for v in self.dset.values() for x in v]:
print(str(n) + " is already in the Diset")
# If the num alue is not already in the repkey values list, processes normally
else:
# If the rep is already in the value list, it will only append num alue to list
if rep in [x for v in self.dset.values() for x in v]:
self.dset.setdefault(rep, []).append(num)
# If the rep is not already in the value list, it will append first the repkey and then num alue to list
else:
self.dset.setdefault(rep, []).append(rep)
self.dset.setdefault(rep, []).append(num)
#If repkey is not in dictionary does not process and tells user to create set with that repkey first
else:
print(str(rep) + " is not a rep in dictionary, create representative first")
# If rep is not a number, does not process and prints error message
except ValueError:
print(str(num) + " is not a number, try again")
def Findset(self,num):
"""Finds the set where num alue is cointained and returns the repkey"""
# Searches the dictionary's value list for the provided num
# If the num alue is in the value list prints the rep number for that value list
if num in [x for v in self.dset.values() for x in v]:
print([k for k, v in self.dset.items() if num in v])
# If the num alue is not in the dictionary's value list, prints error message
else:
print(str(num) + " is not in dictionary")
def Union(self,rep1, rep2):
"""Joins two sets based on their respective repkey, keeps the first set and appends second set's values to it and then deletes
second key-value pair"""
# If the provided paramters for rep1 and rep2 are cointained in the dictionary's keys will loop through the
# values cointained in rep2's values list and append those value to rep1's value list
if rep1 in self.dset.keys() and rep2 in self.dset.keys():
for i in self.dset[rep2]:
self.dset[rep1].append(i)
#Deletes rep2's key-value pair
self.dset.pop(rep2)
# If the provided parameters for rep1 and rep2 are not cointained in the dicitonary's keys will print
# error message
else:
print(str(rep1) + " and "+ str(rep2) +" are not rep values, try again")
def __str__(self):
"""Returns a string representation of self"""
print("The content of the diset: ")
for i in self.dset.values():
st= str(i) + ": representative is " + str(i[0])
print(st)
S = Diset()
for i in [3,5,8,13]:
S.Makeset(i)
for i in [1,2,4]:
S.Addtoset(3,i)
for i in [6]:
S.Addtoset(5,i)
for i in [7,9,11,12,14]:
S.Addtoset(8,i)
for i in [10,15]:
S.Addtoset(13,i)
78 def _str__(self): 79 80 81 82 83 84 85 86SDiset() 87 for i in [3,5,8,13]: 88 S.Makeset(i) 89 for i in [1,2,4]: 90S.Addtoset(3,i) 91 for i in [6]: 92S. Addtoset(5,i) 93 for i in [7,9,11,12,14]: """Returns a string representation of self" print("The content of the diset: ") fori in self.dset.values( st: str(i) print (st) ": representative is " str(i[0]) + + In C116]: print (S) The content of the diset: [8, 7, 9, 11, 12, 141: representative is 8 [3, 1, 2, 4]: representative is 3 [5, 6]: representative is 5 13, 10, 15]: representative is 13 TypeError Traceback (most recent call last) in O 1 print(S) TypeError: __str_returned non-string (type NoneType) In [1171:Explanation / Answer
In Python __str__ needs to return a string. So Please change the definition to
def __str__(self):
st = "The content of the diset: "
for i in self.dset.values():
st= str(i) + ": representative is " + str(i[0])
#Return is Outside the for loop
return st;
Let me know if there is still any error. If yes comment.
Thanks
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.