Module dsa.array

Classes

class Array (contents=None, capacity=10)

A static array implementation in Python

Special Methods:

Index Operator: 
    array[index]

Assignment: 
    array[index] = value

Args

contents

optional container to fill array with default values

capacity

the initial size of the array (defaults to 10)

Expand source code

class Array:
    """ 
    A static array implementation in Python

    Special Methods:

        Index Operator: 
            array[index]
    
        Assignment: 
            array[index] = value
    """
    def __init__(self, contents=None, capacity=10):
        """ 
        Args:
            contents: optional container to fill array with default values
            capacity: the initial size of the array (defaults to 10)
        """
        self._array = [ None ] * capacity
        #: number of elements in array
        self.count = 0

        if contents:
            self.extend(contents)
        
    def append(self, element):
        """
        Append an element. Raise Exception when trying to append more elements than the capacity.

        Args:
            element: the element to append
        """
        if self.count >= self.capacity():
            raise Exception(f"Capacity Error: {len(self)} maximum")

        self._array[self.count] = element
        self.count += 1

    def extend(self, array):
        """ 
        Append each element from a given array. Raise Exception when trying to add more elements than the capacity.
        
        Args:
            array: contains elements to be appended
        """
        for e in array:
            self.append(e)

    def insert(self, index, element):
        """ 
        Insert an element at a specified index.  Raise IndexError if index is out of range.
        
        Args:
            index: index to insert an element
            element: the element to insert
        """
        if index < 0 or index >= self.count:
            raise IndexError

        self.shift_right(self.count, index)
        self._array[index] = element
        self.count += 1
        
    def shift_right(self, start, end):
        """
        a helper method to shift elements to the right

        Args:
            start: starting index of shift
            end: ending index of shift
        """
        for i in range(start, end, -1):
            self._array[i] = self._array[i - 1]

    def delete(self, index):
        """  
        Delete an element at a specified index. Raise IndexError if index is out of range.

        Args:
            index: index of the element to be deleted
        
        """
        if index >= self.count or index < 0:
            raise IndexError

        self.shift_left(index, self.count)
        self.count -= 1

    def shift_left(self, start, end):
        """
        a helper method to shift elements to the right

        Args:
            start: starting index of shift
            end: ending index of shift
        """
        for i in range(start, end):
            self._array[i] = self._array[i + 1]

    ### special methods for handling index operator
    def __getitem__(self, index):
        """
        Returns: 
            the element at the specified index of an array
        """
        if index < 0 or index >= self.count: 
            raise IndexError
        return self._array[index]
            
    def __setitem__(self, index, value):
        """
        set a new value at the specified index of an array
        """
        if index < 0 or index >= self.count: 
            raise IndexError
        self._array[index] = value
        
    ### special methods for len()
    def __len__(self):
        """ 
        Returns: 
            the count of an array
        """
        return self.count

    def capacity(self):
        """ 
        Returns:
            the capacity of an array
        """
        return len(self._array)

    ### override the representation value with the Python interpreter
    def __repr__(self):
        """
        display the contents of the array
        """
        contents = self._array[:self.count]
        return f'{contents} Count: {self.count} Capacity: {self.capacity()}'

Subclasses

• DynamicArray

Instance variables

var count

number of elements in array

Methods

def append(self, element)

Append an element. Raise Exception when trying to append more elements than the capacity.

Args

element

the element to append

Expand source code

def append(self, element):
    """
    Append an element. Raise Exception when trying to append more elements than the capacity.

    Args:
        element: the element to append
    """
    if self.count >= self.capacity():
        raise Exception(f"Capacity Error: {len(self)} maximum")

    self._array[self.count] = element
    self.count += 1

def capacity(self)

Returns

the capacity of an array

Expand source code

def capacity(self):
    """ 
    Returns:
        the capacity of an array
    """
    return len(self._array)

def delete(self, index)

Delete an element at a specified index. Raise IndexError if index is out of range.

Args

index

index of the element to be deleted

Expand source code

def delete(self, index):
    """  
    Delete an element at a specified index. Raise IndexError if index is out of range.

    Args:
        index: index of the element to be deleted
    
    """
    if index >= self.count or index < 0:
        raise IndexError

    self.shift_left(index, self.count)
    self.count -= 1

def extend(self, array)

Append each element from a given array. Raise Exception when trying to add more elements than the capacity.

Args

array

contains elements to be appended

Expand source code

def extend(self, array):
    """ 
    Append each element from a given array. Raise Exception when trying to add more elements than the capacity.
    
    Args:
        array: contains elements to be appended
    """
    for e in array:
        self.append(e)

def insert(self, index, element)

Insert an element at a specified index. Raise IndexError if index is out of range.

Args

index

index to insert an element

element

the element to insert

Expand source code

def insert(self, index, element):
    """ 
    Insert an element at a specified index.  Raise IndexError if index is out of range.
    
    Args:
        index: index to insert an element
        element: the element to insert
    """
    if index < 0 or index >= self.count:
        raise IndexError

    self.shift_right(self.count, index)
    self._array[index] = element
    self.count += 1

def shift_left(self, start, end)

a helper method to shift elements to the right

Args

start

starting index of shift

end

ending index of shift

Expand source code

def shift_left(self, start, end):
    """
    a helper method to shift elements to the right

    Args:
        start: starting index of shift
        end: ending index of shift
    """
    for i in range(start, end):
        self._array[i] = self._array[i + 1]

def shift_right(self, start, end)

a helper method to shift elements to the right

Args

start

starting index of shift

end

ending index of shift

Expand source code

def shift_right(self, start, end):
    """
    a helper method to shift elements to the right

    Args:
        start: starting index of shift
        end: ending index of shift
    """
    for i in range(start, end, -1):
        self._array[i] = self._array[i - 1]

class DynamicArray (contents=None, capacity=10)

A dynamic array implementation in Python

Special Methods:

Index Operator: 
    array[index]

Assignment: 
    array[index] = value

Args

contents

optional container to fill array with default values

capacity

the initial size of the array (defaults to 10)

Expand source code

class DynamicArray(Array):
    """ 
    A dynamic array implementation in Python

    Special Methods:

        Index Operator: 
            array[index]
    
        Assignment: 
            array[index] = value
    """

    def grow(self):
        """ 
        double the capacity of the current array 
        """
        new_size = len(self._array) * 2
        new_array = [ None ] * new_size

        # copy elements
        for i in range(len(self._array)):
            new_array[i] = self._array[i]

        self._array = new_array

    def shrink(self):
        """ 
        halve the capacity of the current array 
        """
        new_size = len(self._array) // 2
        new_array = [ None ] * new_size
        
        # copy elements
        for i in range(new_size):
            new_array[i] = self._array[i]

        self._array = new_array

    def check_capacity(self):
        """ 
        if count >= capacity, grow the array
        if count <= 1/4 of capacity, shrink the array
        """
        if self.count >= len(self._array):
            self.grow()
        elif self.count * 4 <= len(self._array):
            self.shrink()

    def append(self, element):
        """
        Append an element. Raise Exception if trying to append more elements than the capacity.

        Args:
            element: the element to append

        """
        self.check_capacity()

        self._array[self.count] = element
        self.count += 1

    def extend(self, array):
        """ 
        Append each element from a given array. Raise Exception if trying to add more elements than the capacity.
        
        Args:
            array: contains elements to be appended
        """
        for e in array:
            self.append(e)

    def insert(self, index, element):
        """  
        Insert an element at a specified index. Raise IndexError if index is out of range.

        Args:
            index: index to insert an element
            element: the element to insert

        """
        if index >= self.count or index < 0:
            raise IndexError

        self.check_capacity()

        self.shift_right(self.count, index)
        self._array[index] = element
        self.count += 1
        
    def delete(self, index):
        """  
        Delete an element at a specified index. Raise IndexError if index is out of range.

        Args:
            index: index of the element to be deleted
        
        """
        if index >= self.count or index < 0:
            raise IndexError

        self.check_capacity()

        self.shift_left(index, self.count)
        self.count -= 1

Ancestors

• Array

Methods

def append(self, element)

Append an element. Raise Exception if trying to append more elements than the capacity.

Args

element

the element to append

Expand source code

def append(self, element):
    """
    Append an element. Raise Exception if trying to append more elements than the capacity.

    Args:
        element: the element to append

    """
    self.check_capacity()

    self._array[self.count] = element
    self.count += 1

def check_capacity(self)

if count >= capacity, grow the array if count <= 1/4 of capacity, shrink the array

Expand source code

def check_capacity(self):
    """ 
    if count >= capacity, grow the array
    if count <= 1/4 of capacity, shrink the array
    """
    if self.count >= len(self._array):
        self.grow()
    elif self.count * 4 <= len(self._array):
        self.shrink()

def extend(self, array)

Append each element from a given array. Raise Exception if trying to add more elements than the capacity.

Args

array

contains elements to be appended

Expand source code

def extend(self, array):
    """ 
    Append each element from a given array. Raise Exception if trying to add more elements than the capacity.
    
    Args:
        array: contains elements to be appended
    """
    for e in array:
        self.append(e)

def grow(self)

double the capacity of the current array

Expand source code

def grow(self):
    """ 
    double the capacity of the current array 
    """
    new_size = len(self._array) * 2
    new_array = [ None ] * new_size

    # copy elements
    for i in range(len(self._array)):
        new_array[i] = self._array[i]

    self._array = new_array

def insert(self, index, element)

Insert an element at a specified index. Raise IndexError if index is out of range.

Args

index

index to insert an element

element

the element to insert

Expand source code

def insert(self, index, element):
    """  
    Insert an element at a specified index. Raise IndexError if index is out of range.

    Args:
        index: index to insert an element
        element: the element to insert

    """
    if index >= self.count or index < 0:
        raise IndexError

    self.check_capacity()

    self.shift_right(self.count, index)
    self._array[index] = element
    self.count += 1

def shrink(self)

halve the capacity of the current array

Expand source code

def shrink(self):
    """ 
    halve the capacity of the current array 
    """
    new_size = len(self._array) // 2
    new_array = [ None ] * new_size
    
    # copy elements
    for i in range(new_size):
        new_array[i] = self._array[i]

    self._array = new_array

Inherited members

• Array:
  • capacity
  • count
  • delete
  • shift_left
  • shift_right