Nodejs Array Transpose transpose()

Method Source Code

util = require('util');

// some useful functions

var identity = function(x) {
  return x;//from   w w  w  .j a v  a2 s.c o m
};

var pair = function(a, b){
  return [a, b];
};

var isArray = function(a) {
  // from Crockford's book, p 61
  return a && typeof a === 'object' && a.constructor === Array;
};


// Array extensions

Array.prototype.transpose = function() {
  var t = [], n = this.length;
  var m = 0;
  for (var i=0; i < n; i++) {
    var col = this[i];
    if (!isArray(col)) { throw {
      name: 'invalidArgument',
      message: 'transpose method can only be applied to arrays of arrays'
    };}
    if (m == 0) {
      m = col.length;
    }
    else {
      if (m != col.length) {throw {
        name: 'invalidArgument',
        message: 'transpose method can only be applied to arrays of arrays all the same length'
      };}
    }
  }
  for (i=0; i < m; i++) {
    t[i] = [];
    for (var j=0; j < n; j++) {
      t[i][j] = this[j][i];
    }
  }
  return t;
};

Array.prototype.zip = function(a, f) {
  var combine = f || pair;
  if (this.length != a.length) {
    throw {
      name: 'invalidArgument',
      message: 'zip method can only be applied to an array of the same length as its receiver'
    };
  }
  var z = [];
  for (var i=0; i < this.length; i++) {
    z[i] = combine(this[i], a[i]);
  }
  return z;
};

Array.prototype.flatten = function() {
  var flattenIt = function(el) {
    return isArray(el)? el.flatten(): el;
  }
  return this.reduce(function(f, el, i, a) { return f.concat(flattenIt(el)); }, []);
};

Related

1. transpose()

   Array.prototype.transpose = function() {
     var newArr = []
     for (var i = 0; i <= 2; i++) {
       newArr.push([]);
       for (var j = 0; j <= 2; j ++) {
         var originalElement = this[i][j];
         newArr[i].push(this[j][i]);
     return newArr;
   };
   console.log([[1, 2, 3], [4, 5, 6], [7, 8, 9]].transpose())
   

2. transpose()

   Array.prototype.transpose = function () {
     var transposed = [[],[],[]];
     for( var i = 0; i < this.length; i++) {
       for( var j = 0; j < this[i].length; j++) {
         var new_val = this[j][i]
         transposed[i][j] = new_val;
       };
     };
     return transposed;
   ...
   

3. transpose()

   Array.prototype.transpose = function () {
     var columns = [];
     for (var i = 0; i < this[0].length; i++) {
       columns.push([]);
     for (var i = 0; i < this.length; i++) {
       for (var j = 0; j < this[i].length; j++) {
         columns[j].push(this[i][j]);
     return columns;
   };
   

4. transpose()

   Array.prototype.transpose = function() {
     var a = this,
       w = a.length ? a.length : 0,
       h = a[0] instanceof Array ? a[0].length : 0;
     if(h === 0 || w === 0) { return []; }
     var i, j, t = [];
     for(i=0; i<h; i++) {
       t[i] = [];
       for(j=0; j<w; j++) {
   ...
   

5. transpose()

   Array.prototype.transpose = function () {
     var transpose = [];
     for (var i = 0; i < this[0].length; i++) {
       var row = [];
       for (var j = 0; j < this.length; j++) {
         row.push(this[j][i]);
       transpose.push(row);
     return transpose;
   };
   

6. transpose()

   Array.prototype.transpose = function () {
     const transposed = [];
     const rows = this.length;
     const cols = this[0].length;
     for (let c = 0; c < cols; c++) {
       let row = [];
       for (let r = 0; r < rows; r++) {
         row.push(this[r][c]);
       transposed.push(row);
     return transposed;
   };
   const arr1 = [1, 2, 2, 4, 6, 6];
   const arr2 = [1, 0, -1, 2, -2];
   const mat = [[1,2,3], [4,5,6]];
   

7. transpose()

   'use strict';
   Array.prototype.transpose = function() {
     if(this.length === 0) return [];
     if(this[0].length === 0) return [[]];
     let transposeArray = [];
     for(let i = 0, j = this[0].length; i < j; i++) {
       transposeArray[i] = [];
       for(let x = 0, y = this.length; x < y; x++) {
         transposeArray[i].push(this[x][i]);
   ...