Method __delitem__

data_structures/hashing/hash_map.py:206–265

>>> hm = HashMap(5) >>> hm._add_item(1, 10) >>> hm._add_item(2, 20) >>> hm._add_item(3, 30) >>> hm.__delitem__(3) >>> hm HashMap(1: 10, 2: 20) >>> hm = HashMap(5) >>> hm._add_item(-5, 10) >>> hm._add_item(6, 30)

(self, key: KEY)

        self._add_item(key, val)

    def __delitem__(self, key: KEY) -> None:
        """
        >>> hm = HashMap(5)
        >>> hm._add_item(1, 10)
        >>> hm._add_item(2, 20)
        >>> hm._add_item(3, 30)
        >>> hm.__delitem__(3)
        >>> hm
        HashMap(1: 10, 2: 20)
        >>> hm = HashMap(5)
        >>> hm._add_item(-5, 10)
        >>> hm._add_item(6, 30)
        >>> hm._add_item(-7, 20)
        >>> hm.__delitem__(-5)
        >>> hm
        HashMap(6: 30, -7: 20)

        # Trying to remove a non-existing item
        >>> hm = HashMap(5)
        >>> hm._add_item(1, 10)
        >>> hm._add_item(2, 20)
        >>> hm._add_item(3, 30)
        >>> hm.__delitem__(4)
        Traceback (most recent call last):
        ...
        KeyError: 4

        # Test resize down when sparse
        ## Setup: resize up
        >>> hm = HashMap(initial_block_size=100, capacity_factor=0.75)
        >>> len(hm._buckets)
        100
        >>> for i in range(75):
        ...     hm[i] = i
        >>> len(hm._buckets)
        100
        >>> hm[75] = 75
        >>> len(hm._buckets)
        200

        ## Resize down
        >>> del hm[75]
        >>> len(hm._buckets)
        200
        >>> del hm[74]
        >>> len(hm._buckets)
        100
        """
        for ind in self._iterate_buckets(key):
            item = self._buckets[ind]
            if item is None:
                raise KeyError(key)
            if item is _deleted:
                continue
            if item.key == key:
                self._buckets[ind] = _deleted
                self._len -= 1
                break