Convert a Vector into a Matrix | Linear List into a Table | Expand Vector, Flatten Matrix

gistfile1.js

//lo sauer
//fn:Array1dTo2d 1D array to 2D array
//@param a {Array}: list of elements
//@param len {Int}: number of elements in each row
Array1dTo2d = function(a, len){
  var b=[];
  for(var i=0; i<a.length; i+=len)
  	b.push( a.slice(i,i+len) );
  return b;
}
Array1dTo2d([1,2,3,4,5,6,7,8,9,10,11,12],3);
//> [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]


//fn:Matrix: converts linear list of list elements into an nxm matrix
//@param alist {Array}: linear list of elements 
//@param n {Int}: #rows of the matrix
//@param m {Int}: #rows of the matrix optional:true; else n=m
function Matrix(alist,n,m) {
	m||(m = n);
	var mat = []
	for(var i=0,len=n*m;i<len;i+=m)
		mat.push(alist.slice(i,i+m))
	return mat;
}

Matrix([1,2,3,4,5,6,7,8,9,10,11,12],3);
//> [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
Matrix([1,2,3,4,5,6,7,8,9,10,11,12],3,4);
//> [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
Matrix([1,2,3,4,5,6,7,8,9,10,11,12],4,3);
//> [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]

//fn:List
//reverse operation to 'Matrix': flattens an array
//@param mat {Array}:
function List(mat){
	return (mat+'').split(',').map(parseFloat);
}
List(Matrix([1,2,3,4,5,6,7,8,9,10,11,12],3,4));
//> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

list_to_array.coffee

### lo sauer, 2011
fn:Array1dTo2d 1D array to 2D array
@param a {Array}: list of elements
@param len {Int}: number of elements in each row
###
Array1dTo2d = (a, len) ->
  b = []
  i = 0
  while i < a.length
    b.push a.slice(i, i + len)
    i += len
  b
Array1dTo2d [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ], 3
#> [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]

Matrix = (alist, n, m) ->
  m or (m = n)
  mat = []
  i = 0
  len = n * m

  while i < len
    mat.push alist.slice(i, i + m)
    i += m
  mat
Matrix [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ], 3
Matrix [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ], 3, 4
Matrix [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ], 4, 3
#> [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ], [ 10, 11, 12 ] ]

List = (mat) ->
  (mat + "").split(",").map parseFloat
List Matrix([ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ], 3, 4)
#> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]