Bit of a theoretical question, if I had a JavaScript application where I have multiple Players and for each player there will be 100 computer generated maths questions.
In single player mode it's easy, just generating the questions for the one player:
var player1Qs = [];
for (i = 0; i < maxQustions; i++) {
// Generate Question Object
var question = {};
...
// Add to Array
player1Qs.push(question);
}
That works with no issue. However, when I add a second player into the mix using the same sort of idea as above is where I get a bit puzzled. I'm tryinng to do it without using a multi-dimensional array becasue I'm trying to keep it as simple as possible, but it might be unavoidable.
So player 2 would look something similar to this:
var player1Qs = [];
var player2Qs = [];
for (i = 0; i < playerCount; i++) {
for (j = 0; j < maxQustions; j++) {
// Generate Question Object
var question = {};
...
// Add to Array
???
}
}
Would there be a way of me adding to those two arrays dynamically using a for loop? Or would I need a containing array of players and inside that an array for the questions?
Something like this should do the trick:
// Make sure all players exist.
var players = [];
for (var i = 0; i < playerCount; i++) {
players.push({ name: "Player " + i, questions: [] });
}
// Create questions
for (var i = 0; i < maxQuestions; i++) {
// Generate Question Object
var question = {};
// Do stuff with this question
// Assign the current question to all players.
for (var j = 0; j < playerCount; j++) {
players[j].questions.push(question);
}
}
I'm tryinng to do it without using a multi-dimensional array becasue I'm trying to keep it as simple as possible
I would argue that having a two-dimentional array is the simplest use-case, as you suggest in your question:
Or would I need a containing array of players and inside that an array
for the questions?
The answer is yes (at least if you want to keep it simple). The players array will keep all the players, and each player can then have 100 questions each.
var maxQustions = 100;
var players= []
var player1Qs = [];
var player2Qs = [];
players.push(player1Qs);
players.push(player2Qs);
for (i = 0; i < players.length; i++) {
for (j = 0; j < maxQustions; j++) {
var question = {};
players[i].push(question);
}
}
follow this approach, I assume you have dynamic players and its array:-
var data = {};
var player = [1,2]
var c = [1,2,3,4,5]
for(j=0;j<player.length;j++)
{
data['players'] = player;
data['questions'] = c
}
console.log(data)
Related
Apologies if this has been asked before - I couldn't find what I was looking for after a search, but I'm a beginner, so I might have missed something.
I am trying to implement Lloyd's algorithm in JavaScript (very crudely) to get some practice.
var k_means = function (array,number_clusters,max_loops) {
var initial_centers = underscore.sample(shelter_lat_lon,number_clusters);
var current_centers = initial_centers;
var current_associations = {};
for (p = 0; p < current_centers.length; p++) {
current_associations[current_centers[p]] = []
}
for (loops = 0; loops < max_loops; loops++) {
for (i = 0; i < array.length; i++) {
var current_loc = array[i]
temp_array = new Array();
for (j = 0; j < current_centers.length; j++) {
var distance_from_center = distance(current_centers[j],current_loc)
temp_array.push(distance_from_center)
}
var closest_center_lat_lon = current_centers[smallest_index(temp_array)]
current_associations[closest_center_lat_lon].push(current_loc)
}
new_clusters_temp = []
for (var key in current_associations) {
lat = []
lon = []
for (i = 0; i < current_associations[key].length; i++){
lat.push(current_associations[key][i][0])
lon.push(current_associations[key][i][1])
}
mean_lat = math_module.mean(lat)
mean_lon = math_module.mean(lon)
new_clusters_temp.push([mean_lat,mean_lon])
}
current_centers = new_clusters_temp;
}
}
Sorry for the ugly code. There are 2 module requirements - underscore and mathjs (mathjs is called math_module). Additionally, the function distance returns the Euclidean distance (I'm using 2 dimensional data), and smallest_index returns the index of the smallest element in an array.
The only problem I'm having is coming at the line
current_centers = new_clusters_temp;
Node returns the error "Cannot read property 'push' of undefined." After debugging a bit, it essentially thinks the array "current_centers" is empty. In Python, this is how I would reassign a list outside of a for loop. Is this different in JavaScript?
Cheers!
Alex
I'm working on Google Script and I'm testing different ways to create two dimensions arrays.
I have created an array like this:
var codes = new Array(6);
for (var i = 0; i < 6; i++) {
codes[i] = new Array(4);
}
codes[0][0]="x";
codes[0][1]="x";
codes[0][2]="x";
codes[0][3]="x";
codes[1][0]="x";
codes[1][1]="x";
codes[1][2]="x";
codes[1][3]="x";
codes[2][0]="x";
codes[2][1]="x";
codes[2][2]="x";
codes[2][3]="x";
codes[3][0]="x";
codes[3][1]="x";
codes[3][2]="x";
codes[3][3]="x";
codes[4][0]="x";
codes[4][1]="x";
codes[4][2]="x";
codes[4][3]="x";
codes[5][0]="x";
codes[5][1]="x";
codes[5][2]="x";
codes[5][3]="x";
And it is working fine.
I read following links here, here and here.
But when I do it like this:
var codes = new Array(6);
for (var i = 0; i < 6; i++) {
codes[i] = new Array(4);
}
codes[0]=["x","x","x","x"];
codes[1]=["x","x","x","x"];
codes[2]=["x","x","x","x"];
codes[3]=["x","x","x","x"];
codes[4]=["x","x","x","x"];
codes[5]=["x","x","x","x"];
It didn't work, so I tried like this:
var codes = new Array([["x","x","x","x"],["x","x","x","x"],["x","x","x","x"],["x","x","x","x"],["x","x","x","x"],["x","x","x","x"]]);
it didn't work either.
When the code don't work, I get no error, just no display of the values.
What am I doing wrong? It looks to be the same code and the two not working ways are recommended in many documentations.
W3schools says that there is no need to use new Array().
For simplicity, readability and execution speed, use literal method ex:
var animals = ["cat", "rabbit"];
Reason why your code was not working is that you're equaling codes inside the loop and after end of loop scope 'codes' is getting only the last set array. Instead you should push those arrays to codes.
var codes = [];
for (var i = 0; i < 6; i++) {
codes.push([i]);
}
console.log(codes)
codes[0]=["x","x","x","x"];
codes[1]=["x","x","x","x"];
codes[2]=["x","x","x","x"];
codes[3]=["x","x","x","x"];
codes[4]=["x","x","x","x"];
codes[5]=["x","x","x","x"];
Better yet, two for loops to create the double array:
var codes = [], // Initiate as array, in Javascript this is actually fastre than using new (I don't know any cases you should use new)
rows = 6,
columns = 6;
for (var i = 0; i < rows; i++){
codes.push([]); // Initiate
for (var j = 0; j < columns; j++){
codes[i][j] = 'x';
}
}
Other idea, pre-initiate an array with the correct columns then copy:
var arrTemp = [],
codes = [],
rows = 6,
columns = 6;
for (var j = 0; j < columns; j++)
arrTemp[i] = 'x';
for (var i = 0; i < rows; i++)
codes.push( arrTemp.slice(0) ); // If you just push the array without slice it will make a reference to it, not copy
Other way to pre-initiate the array with 'x's:
arrTemp = Array.apply(null, Array(columns)).map(function () {return 'x'});
There might be a very simple solution my problem but just not being able to find one so please help me to get to my solution in the simplest way...
The issue here is that I have data being displayed in a tabular form. Each row has 5 columns and in one of the columns it shows multiple values and so that's why I need to refer to a value by something like this row[1]['value1'], row[1]['value2'] & then row[2]['value1'], row[2]['value2'].
I declare the array
var parray = [[],[]];
I want to store the values in a loop something like this
for(counter = 0; counter < 10; counter ++){
parray[counter]['id'] += 1;
parray[counter]['isavailable'] += 0;
}
Later I want to loop through this and get the results:
for (var idx = 0; idx < parray.length; idx++) {
var pt = {};
pt.id = parray[schctr][idx].id;
pt.isavailable = parray[schctr][idx].isavailable;
}
Obviously iit's not working because Counter is a numeric key and 'id' is a string key ..my question how do I achieve this ??
Thanks for all the answers in advance.
JS has no concept of "associative arrays". You have arrays and objects (map). Arrays are objects though, and you can put keys, but it's not advisable.
You can start off with a blank array
var parray = [];
And "push" objects into it
for(counter = 0; counter < 10; counter++){
parray.push({
id : 1,
isAvailable : 0
});
}
Then you can read from them
for (var idx = 0; idx < parray.length; idx++) {
// Store the current item in a variable
var pt = parray[idx];
console.log(pt);
// read just the id
console.log(parray[idx].id);
}
Like I did here
What you want inside your array is just a plain object:
// just a regular array
var parray = [];
for(var counter = 0; counter < 10; counter++){
// create an object to store the values
var obj = {};
obj.id = counter;
obj.isavailable = 0;
// add the object to the array
parray.push(obj);
}
later:
for (var idx = 0; idx < parray.length; idx++) {
var pt = parray[idx];
// do something with pt
}
I have the following javascript
information0 = xmlDoc.getElementsByTagName("info")[0].textContent;
information1 = xmlDoc.getElementsByTagName("info")[1].textContent;
information2 = xmlDoc.getElementsByTagName("info")[2].textContent;
information3 = xmlDoc.getElementsByTagName("info")[3].textContent;
information4 = xmlDoc.getElementsByTagName("info")[4].textContent;
information5 = xmlDoc.getElementsByTagName("info")[5].textContent;
information6 = xmlDoc.getElementsByTagName("info")[6].textContent;
I want to create a new var for each index number. There are 600 in total. How can I do this using a for loop?
Thanks in advance
The best thing here is to use an array, not a bunch of individual variables.
var information = [];
var index;
var info = xmlDoc.getElementsByTagName("info");
for (index = 0; index < info.length; ++index) {
information[index] = info[index].textContent;
}
Um... use an array? Also, don't call getElementsByTagName repeatedly, it's expensive!
var tags = xmlDoc.getElementsByTagName('info'), l = tags.length, i, information = [];
for( i=0; i<l; i++) information[i] = tags[i].textContent;
If you're in a reasonably up-to-date browser:
var information = [].map.call(xmlDoc.getElementsByTagName('info'),function(a) {return a.textContent;});
Like this:
var information = [],
i,
elements = xmlDoc.getElementsByTagName("info"),
n = elements.length;
for (i = 0; i < n; ++i) {
information[i] = elements[i].textContent;
}
You need to use an array.
var infoTags = xmlDoc.getElementsByTagName("info"),
i = 0,
len = infoTags.length,
values = []; //array literal syntax, you could also use new Array()
for (; i < len; i++) {
values.push(infoTags[i].textContent); //push the textContent into the array
}
Things that you should note:
I cached the result of getElementsByTagName instead of performing the query multiple times.
I cached the length property of infoTags. That avoids multiple property lookups to access infoTags.length on every iterations. Property lookups are expensive in JavaScript.
To know how you can work with arrays, have a look at the Array object.
-
Ok i'v been trying many deferent things to get this to work.
I need a string separated by commas into a 2 dimensional array... like this for example:
string = "a,b,c,d,e,1,2,3,4,5";
array = [['a','1'],['b','2'],['c','3'],['d','4'],['e','5']];
This is the code I have been tweaking.
var temp = list.split(',');
questions = [[''],[''],[''],[''],['']];
five = 0;
one = 0;
for(var i = 0; i < temp.length; i++) {
if(one == 5){five++; one = 0;}
one++;
questions[one][five] = temp[i];
}
btw list = "a,b,c,d,e,1,2,3,4,5".
Thank's in advance!!!
I'd suggest a slightly different approach, that avoids the (to my mind overly-) complex internals of the for loop:
var string = "a,b,c,d,e,1,2,3,4,5",
temp = string.split(','),
midpoint = Math.floor(temp.length/2),
output = [];
for (var i=0, len=midpoint; i<len; i++){
output.push([temp[i], temp[midpoint]]);
midpoint++;
}
console.log(output);
JS Fiddle demo.
OK so i fixed it before i asked the question... but i did so much work i'll post it anyway.
This is the code i have now that works:
var temp = list.split(',');
questions = [[],[],[],[],[]];
for(var i = 0; i < temp.length; i++) {
questions[i%5][Math.floor(i/5)] = temp[i];
one++;
}
Thank You Barmar!!!