HashMaps/hash_map_sc.py

# Name: Andrew Scott
# OSU Email: scottand@oregonstate.edu
# Course: CS261 - Data Structures
# Assignment: 6
# Due Date: 2022-06-03
# Description: HashMap implementation using Separate Chaining


from a6_include import DynamicArray, LinkedList, SLNode, hash_function_1, hash_function_2


class HashMap:
    def __init__(self, capacity: int, function) -> None:
        """
        Initialize new HashMap that uses
        separate chaining for collision resolution
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        self._buckets = DynamicArray()
        for _ in range(capacity):
            self._buckets.append(LinkedList())

        self._capacity = capacity
        self._hash_function = function
        self._size = 0

    def __str__(self) -> str:
        """
        Override string method to provide more readable output
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        out = ""
        for i in range(self._buckets.length()):
            out += str(i) + ": " + str(self._buckets[i]) + "\n"
        return out

    def get_size(self) -> int:
        """
        Return size of map
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        return self._size

    def get_capacity(self) -> int:
        """
        Return capacity of map
        DO NOT CHANGE THIS METHOD IN ANY WAY
        """
        return self._capacity

    # ------------------------------------------------------------------ #

    def put(self, key: str, value: object) -> None:
        """Adds (or updates) a key/value pair to the hash map

        Parameters
        ----------
        key : str
            Identifier for the given value
        value : object
            Value to add, or update if the key is already present
        """

        hash = self._hash_function(key)
        index = hash % self._capacity
        node = self._buckets[index].contains(key)
        if node is None:
            self._buckets[index].insert(key, value)
            self._size += 1
        else:
            node.value = value

    def empty_buckets(self) -> int:
        """Gets the number of empty buckets in the hash table

        Returns
        -------
        int
            Number of empty buckets
        """

        count = 0
        for index in range(self._capacity):
            if self._buckets[index].length() == 0:
                count += 1
        return count

    def table_load(self) -> float:
        """Get the current hash table load factor

        Returns
        -------
        float
            The load factor
        """

        return self._size / self._capacity

    def clear(self) -> None:
        """Clear the contents of the hash map without changing its capacity"""
        for index in range(self._capacity):
            if self._buckets[index].length() != 0:
                self._buckets[index] = LinkedList()
        self._size = 0


    def resize_table(self, new_capacity: int) -> None:
        """
        TODO: Write this implementation
        """
        pass

    def get(self, key: str) -> object:
        """
        TODO: Write this implementation
        """
        pass

    def contains_key(self, key: str) -> bool:
        """
        TODO: Write this implementation
        """
        pass

    def remove(self, key: str) -> None:
        """
        TODO: Write this implementation
        """
        pass

    def get_keys(self) -> DynamicArray:
        """
        TODO: Write this implementation
        """
        pass


def find_mode(da: DynamicArray) -> (DynamicArray, int):
    """
    TODO: Write this implementation
    """
    # if you'd like to use a hash map,
    # use this instance of your Separate Chaining HashMap
    map = HashMap(da.length() // 3, hash_function_1)


# ------------------- BASIC TESTING ---------------------------------------- #

if __name__ == "__main__":

    print("\nPDF - put example 1")
    print("-------------------")
    m = HashMap(50, hash_function_1)
    for i in range(150):
        m.put("str" + str(i), i * 100)
        if i % 25 == 24:
            print(m.empty_buckets(), m.table_load(), m.get_size(), m.get_capacity())

    print("\nPDF - put example 2")
    print("-------------------")
    m = HashMap(40, hash_function_2)
    for i in range(50):
        m.put("str" + str(i // 3), i * 100)
        if i % 10 == 9:
            print(m.empty_buckets(), m.table_load(), m.get_size(), m.get_capacity())

    print("\nPDF - empty_buckets example 1")
    print("-----------------------------")
    m = HashMap(100, hash_function_1)
    print(m.empty_buckets(), m.get_size(), m.get_capacity())
    m.put("key1", 10)
    print(m.empty_buckets(), m.get_size(), m.get_capacity())
    m.put("key2", 20)
    print(m.empty_buckets(), m.get_size(), m.get_capacity())
    m.put("key1", 30)
    print(m.empty_buckets(), m.get_size(), m.get_capacity())
    m.put("key4", 40)
    print(m.empty_buckets(), m.get_size(), m.get_capacity())

    print("\nPDF - empty_buckets example 2")
    print("-----------------------------")
    m = HashMap(50, hash_function_1)
    for i in range(150):
        m.put("key" + str(i), i * 100)
        if i % 30 == 0:
            print(m.empty_buckets(), m.get_size(), m.get_capacity())

    print("\nPDF - table_load example 1")
    print("--------------------------")
    m = HashMap(100, hash_function_1)
    print(m.table_load())
    m.put("key1", 10)
    print(m.table_load())
    m.put("key2", 20)
    print(m.table_load())
    m.put("key1", 30)
    print(m.table_load())

    print("\nPDF - table_load example 2")
    print("--------------------------")
    m = HashMap(50, hash_function_1)
    for i in range(50):
        m.put("key" + str(i), i * 100)
        if i % 10 == 0:
            print(m.table_load(), m.get_size(), m.get_capacity())

    print("\nPDF - clear example 1")
    print("---------------------")
    m = HashMap(100, hash_function_1)
    print(m.get_size(), m.get_capacity())
    m.put("key1", 10)
    m.put("key2", 20)
    m.put("key1", 30)
    print(m.get_size(), m.get_capacity())
    m.clear()
    print(m.get_size(), m.get_capacity())

    print("\nPDF - clear example 2")
    print("---------------------")
    m = HashMap(50, hash_function_1)
    print(m.get_size(), m.get_capacity())
    m.put("key1", 10)
    print(m.get_size(), m.get_capacity())
    m.put("key2", 20)
    print(m.get_size(), m.get_capacity())
    m.resize_table(100)
    print(m.get_size(), m.get_capacity())
    m.clear()
    print(m.get_size(), m.get_capacity())

    print("\nPDF - resize example 1")
    print("----------------------")
    m = HashMap(20, hash_function_1)
    m.put("key1", 10)
    print(m.get_size(), m.get_capacity(), m.get("key1"), m.contains_key("key1"))
    m.resize_table(30)
    print(m.get_size(), m.get_capacity(), m.get("key1"), m.contains_key("key1"))

    print("\nPDF - resize example 2")
    print("----------------------")
    m = HashMap(75, hash_function_2)
    keys = [i for i in range(1, 1000, 13)]
    for key in keys:
        m.put(str(key), key * 42)
    print(m.get_size(), m.get_capacity())

    for capacity in range(111, 1000, 117):
        m.resize_table(capacity)

        m.put("some key", "some value")
        result = m.contains_key("some key")
        m.remove("some key")

        for key in keys:
            # all inserted keys must be present
            result &= m.contains_key(str(key))
            # NOT inserted keys must be absent
            result &= not m.contains_key(str(key + 1))
        print(
            capacity, result, m.get_size(), m.get_capacity(), round(m.table_load(), 2)
        )

    print("\nPDF - get example 1")
    print("-------------------")
    m = HashMap(30, hash_function_1)
    print(m.get("key"))
    m.put("key1", 10)
    print(m.get("key1"))

    print("\nPDF - get example 2")
    print("-------------------")
    m = HashMap(150, hash_function_2)
    for i in range(200, 300, 7):
        m.put(str(i), i * 10)
    print(m.get_size(), m.get_capacity())
    for i in range(200, 300, 21):
        print(i, m.get(str(i)), m.get(str(i)) == i * 10)
        print(i + 1, m.get(str(i + 1)), m.get(str(i + 1)) == (i + 1) * 10)

    print("\nPDF - contains_key example 1")
    print("----------------------------")
    m = HashMap(10, hash_function_1)
    print(m.contains_key("key1"))
    m.put("key1", 10)
    m.put("key2", 20)
    m.put("key3", 30)
    print(m.contains_key("key1"))
    print(m.contains_key("key4"))
    print(m.contains_key("key2"))
    print(m.contains_key("key3"))
    m.remove("key3")
    print(m.contains_key("key3"))

    print("\nPDF - contains_key example 2")
    print("----------------------------")
    m = HashMap(75, hash_function_2)
    keys = [i for i in range(1, 1000, 20)]
    for key in keys:
        m.put(str(key), key * 42)
    print(m.get_size(), m.get_capacity())
    result = True
    for key in keys:
        # all inserted keys must be present
        result &= m.contains_key(str(key))
        # NOT inserted keys must be absent
        result &= not m.contains_key(str(key + 1))
    print(result)

    print("\nPDF - remove example 1")
    print("----------------------")
    m = HashMap(50, hash_function_1)
    print(m.get("key1"))
    m.put("key1", 10)
    print(m.get("key1"))
    m.remove("key1")
    print(m.get("key1"))
    m.remove("key4")

    print("\nPDF - get_keys example 1")
    print("------------------------")
    m = HashMap(10, hash_function_2)
    for i in range(100, 200, 10):
        m.put(str(i), str(i * 10))
    print(m.get_keys())

    m.resize_table(1)
    print(m.get_keys())

    m.put("200", "2000")
    m.remove("100")
    m.resize_table(2)
    print(m.get_keys())

    print("\nPDF - find_mode example 1")
    print("-----------------------------")
    da = DynamicArray(["apple", "apple", "grape", "melon", "melon", "peach"])
    map = HashMap(da.length() // 3, hash_function_1)
    mode, frequency = find_mode(da)
    print(f"Input: {da}\nMode: {mode}, Frequency: {frequency}")

    print("\nPDF - find_mode example 2")
    print("-----------------------------")
    test_cases = (
        [
            "Arch",
            "Manjaro",
            "Manjaro",
            "Mint",
            "Mint",
            "Mint",
            "Ubuntu",
            "Ubuntu",
            "Ubuntu",
            "Ubuntu",
        ],
        ["one", "two", "three", "four", "five"],
        ["2", "4", "2", "6", "8", "4", "1", "3", "4", "5", "7", "3", "3", "2"],
    )

    for case in test_cases:
        da = DynamicArray(case)
        map = HashMap(da.length() // 3, hash_function_2)
        mode, frequency = find_mode(da)
        print(f"Input: {da}\nMode: {mode}, Frequency: {frequency}\n")