lab2_listbag

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Carleton University *

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Course

2100

Subject

Computer Science

Date

Feb 20, 2024

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# SYSC 2100 Winter 2024 Lab 2 # An implementation of ADT Bag that uses an instance of Python's built-in # list type as the underlying data structure. import random __author__ = 'Belal Alobieda' __student_number__ = '101151327' class ListBag: def __init__(self, iterable=[]) -> None: """Initialize this ListBag. If no iterable is provided, the new ListBag is empty. Otherwise, initialize the ListBag by adding the values provided by the iterable. >>> bag = ListBag() >>> bag ListBag([]) >>> bag = ListBag([1, 4, 3, 6, 3]) >>> bag ListBag([1, 4, 3, 6, 3]) """ self._elems = [] for item in iterable: self._elems.append(item) # or, self.add(item) def __str__(self) -> str: """Return a string representation of this ListBag. >>> bag = ListBag() >>> str(bag) '{}' >>> bag = ListBag([1, 4, 3, 6, 3]) >>> str(bag) '{1, 4, 3, 6, 3}' Note: Depending on how __str__ is implemented, the order of the elements in the returned string may be different. """ # Use the string representation of the bag's underlying list, # with the enclosing '[]' replaced by '{}'. s = str(self._elems) return '{' + s[1:len(s) - 1] + '}' def __repr__(self) -> str: """Return the canonical string representation of this ListBag. >>> bag = ListBag() >>> repr(bag) 'ListBag([])' >>> bag = ListBag([3, 1, 2, 3, 4]) >>> repr(bag) 'ListBag([3, 1, 2, 3, 4])'

Note: Depending on how __repr__ is implemented, the order of the list elements in the returned string may be in a different. """ # For a ListBag object, obj, the expression eval(repr(obj)) # returns a new ListBag that is equal to obj. return "{0}({1})".format(self.__class__.__name__, self._elems) # or, return self.__class__.__name__ + '(' + str(self._elems) + ')' def __len__(self) -> int: """Return the number of items in this ListBag. >>> bag = ListBag() >>> len(bag) 0 >>> bag = ListBag([1, 4, 3, 6]) >>> len(bag) 4 """ return len(self._elems) def __iter__(self) -> 'list_iterator': """Return an iterator for this ListBag. >>> bag = ListBag([3, 6, 3]) >>> for x in bag: ... print(x) ... 3 6 3 """ return iter(self._elems) def __contains__(self, item: any) -> bool: """Return True if item is in this ListBag; otherwise False. >>> bag = ListBag() >>> 2 in bag False >>> bag = ListBag([1, 4, 3, 6]) >>> 4 in bag True >>> 7 in bag False """ return item in self._elems def add(self, item: any) -> None: """Add item to this ListBag. >>> bag = ListBag([1, 4, 3, 6]) >>> bag.add(3) >>> len(bag) 5 >>> str(bag) '{1, 4, 3, 6, 3}'

""" self._elems.append(item) def count(self, item: any) -> int: """Return the total number of occurrences of item in this bag. >>> bag = ListBag([3, 1, 2, 3, 4]) >>> bag.count(3) 2 >>> bag.count(7) 0 """ return self._elems.count(item) def remove(self, item: any) -> any: """Remove and return one instance of item from this ListBag. Raises ValueError if the bag is empty. Raises ValueError if item is not in the bag. >>> bag = ListBag([3, 1, 2, 3, 4]) # The bag has 5 elements, including two 3's. >>>len(bag) 5 >>> bag.count(3) 2 # Now remove one 3. >>> bag.remove(3) 3 >>> bag.count(3) 1 >>> len(bag) 4 """ if len(self._elems) == 0: raise ValueError("bag.remove(x): remove from empty bag") elif self._elems.count(item) == 0: raise ValueError("bag.remove(x): x not in bag") else: self._elems.remove(item) return item def grab(self) -> any: """Remove and return a randomly selected item from this bag. Raises ValueError if the bag is empty. >>> bag = ListBag([3, 1, 2, 3, 4]) >>> len(bag) 5 >>> ListBag.grab() # grab will randomly select one of items stored in the bag, # and remove and return that value. The value displayed in the shell # will be one of 1, 2, 3 or 4, depending on which item was removed. >>> len(bag)

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4 """ if len(self._elems) == 0: raise ValueError("bag.grab(): grab from empty bag") else: item = choice(self._elems) self._elems.remove(item) return item def __add__(self, other: 'ListBag') -> 'ListBag': """Return a new ListBag containing the concatenation of self and other. Raises TypeError if other is not a ListBag. >>> bag1 = ListBag([1, 3, 5]) >>> bag2 = ListBag([2, 4, 6]) >>> bag3 = bag1 + bag2 >>> repr(bag3) 'ListBag([1, 3, 5, 2, 4, 6])' Note: Depending on how __add__ and __repr__ are implemented, the order of the elements in the string returned by repr may be different. """ if not isinstance(other, ListBag): raise TypeError("can only concatenate ListBag to ListBag") New_Bag = ListBag(self._elems + other._elems) return New_Bag def __eq__(self, other: 'ListBag') -> bool: """Return True if self is equal to the ListBag referred to by other; otherwise return False. >>> bag1 = ListBag([1, 2, 3]) >>> bag2 = ListBag([3, 2, 1]) >>> bag1 == bag2 True >>> bag1 = ListBag([1, 2, 3]) >>> bag2 = ListBag([4, 5, 6]) >>> bag1 == bag2 False """ if not isinstance(other, ListBag): return False return sorted(self._elems) == sorted(other._elems) def longest_string(in_val): longest = "" for i in in_val: if longest < in_val[i]: longest = in_val[i] return longest

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