array2d.py

class ListOfListArray:
    def __init__(self, width, height, default=None):
        self.width, self.height = width, height
        self.values = [[default] * width for i in range(height)]
    
    def __getitem__(self, (x, y)):
        return self.values[y][x]
    
    def grow_height(self, dy, default=None):
        self.height += dy
        self.values.extend([default] * self.width for i in range(dy))
    
    def grow_width(self, dx, default=None):
        self.width += dx
        for row in self.values:
            row.extend([default] * dy)

def SingleListArray:
    def __init__(self, width, height, default=None):
        self.width, self.height = width, height
        self.values = [default] * (width * height)
    
    def __getitem__(self, (x, y)):
        if 0 <= x < self.width:
            return self.values[x + self.width * y]
        raise IndexError
    
    def grow_height(self, dy, default=None):
        self.height += dy
        self.values.extend([default] * (dy * self.width))
    
    def grow_width(self, dx, default=None):
        new_width = self.width + dx
        new_values = [default] * (new_width * self.height)
        for y in range(self.height):
            for x in range(self.width):
                values[x + new_width * y] = self[x, y]
        self.values = new_values
        self.width = new_width

class DictArray:
    def __init__(self, width, height, default=None):
        self.width, self.height, self.default = width, height, default
        self.values = {}
    
    def __getitem__(self, (x, y)):
        if 0 <= x < self.width and 0 <= y < self.height:
            return self.values.get((x, y), default)
        raise IndexError
    
    def grow_height(self, dy): self.height += dy
    def grow_width(self, dx): self.width += dx