Module forma.cell

Integer point/vector class defining the position of a cell.

The cell class behaves much as a normal 2D vector class, with the restriction that its components must be integer-valued. A subset of normal vector operations are available, namely a vector addition and subtraction, along with a vector equality check.

Along with the cell class definition, a number of distance measures between cell positions are provided. Specifically, the Manhattan, Chebyshev and Euclidean distances.

Functions

new (x, y) Initialise a new forma.cell.
clone (icell) Perform a copy of a cell.

Metamethods

__add (a, b) Add two cell positions
__sub (a, b) Subtract two cell positions
__eq (a, b) Test for equality of two cell vectors.
__tostring (icell) Render a cell as a string.

Distance measures

manhattan (a, b) Manhattan distance between cells.
chebyshev (a, b) Chebyshev distance between cells.
euclidean (a, b) Euclidean distance between cells.
euclidean2 (a, b) Squared Euclidean distance between cells.


Functions

new (x, y)
Initialise a new forma.cell.

Parameters:

  • x first coordinate
  • y second coordinate

Returns:

    new forma.cell

Usage:

    local x, y = 1, 5
    local new_cell = cell.new(x,y)
clone (icell)
Perform a copy of a cell.

Parameters:

  • icell to be copied

Returns:

    copy of icell

Usage:

    local old_cell = cell.new(1,1)
    local new_cell = old_cell:clone()

Metamethods

__add (a, b)
Add two cell positions

Parameters:

  • a first cell
  • b second cell

Returns:

    c = a + b

Usage:

    local c1, c2 = cell.new(1,1), cell.new(0,0)
    local c3 = c2 + c1
    assert(c3 == c1)
__sub (a, b)
Subtract two cell positions

Parameters:

  • a first cell
  • b second cell

Returns:

    c = a - b

Usage:

    local c1, c2 = cell.new(1,1), cell.new(2,2)
    local c3 = c2 - c1
    assert(c3 == c1)
__eq (a, b)
Test for equality of two cell vectors. assert(cell.new(0,1) == cell.new(0,1)

Parameters:

  • a first cell
  • b second cell

Returns:

    a == b
__tostring (icell)
Render a cell as a string.

Parameters:

  • icell the forma.cell being rendered as a string

Returns:

    string of the form (icell.x, icell.y)

Usage:

    print(cell.new(1,1))

Distance measures

manhattan (a, b)
Manhattan distance between cells.

Parameters:

  • a first cell
  • b second cell

Returns:

    L1(a,b) = |a.x-b.x| + |a.y-b.y|

Usage:

    local distance = cell.manhattan(cell.new(1,2), cell.new(3,4))
chebyshev (a, b)
Chebyshev distance between cells.

Parameters:

  • a first cell
  • b second cell

Returns:

    L_inf(a,b) = max(|a.x-b.x|, |a.y-b.y|)

Usage:

    local distance = cell.chebyshev(cell.new(1,2), cell.new(3,4))
euclidean (a, b)
Euclidean distance between cells.

Parameters:

  • a first cell
  • b second cell

Returns:

    L_2(a,b) = sqrt((a-b)^2)

Usage:

    local distance = cell.euclidean(cell.new(1,2), cell.new(3,4))
euclidean2 (a, b)
Squared Euclidean distance between cells. A little faster than cell.euclidean as it avoids the sqrt.

Parameters:

  • a first cell
  • b second cell

Returns:

    L_2(a,b)^2 = (a-b)^2

Usage:

    local distance = cell.euclidean2(cell.new(1,2), cell.new(3,4))
generated by LDoc 1.4.6 Last updated 2019-01-07 21:10:29