I have this simple JSON file that supposed to be one array Paths with 3 arrays (Path1, Path2, Path3) of objects.
{
"Paths":
{
"Path1": [{"x":"4","y":"182"},{"x":"220","y":"186"}],
"Path2": [{"x":"4","y":"222"},{"x":"256","y":"217"}],
"Path3": [{"x":"6","y":"170"},{"x":"216","y":"183"}]
}
}
Considering an online example that I found I am doing this to get the length of Paths node:
// It's Phaser 3 (JS game framework)
// this.cache.json.get('data') -> returns me the JSON contents
var json = this.cache.json.get('data');
for (var pos in json.Paths) {
var len = parseInt(json.Paths[pos].length)+1;
console.log(len);
}
Although it works I would like to know if this is the correct approach because it seems to be too much code only to get a node length.
Thanks!
If you are wanting to get a count of all the points in all paths you could access them using Object.values() and then reduce()
const data ={
"Paths":
{
"Path1": [{"x":"4","y":"182"},{"x":"220","y":"186"}],
"Path2": [{"x":"4","y":"222"},{"x":"256","y":"217"}],
"Path3": [{"x":"6","y":"170"},{"x":"216","y":"183"}]
}
}
const numPoints = Object.values(data.Paths).reduce((a,c) => (a + c.length), 0)
console.log(numPoints)
Not sure if you are trying to print the length of each path or get total length of all paths, if you want to print the length of each path then you can use map
let lengths = Object.values(json.Paths).map(path => path.length + 1)
console.log(lengths)
which will output
[ 3, 3, 3 ]
or forEach like you did
Object.values(json.Paths).forEach(path => console.log(path.length + 1))
if you need the total you can use reduce
let nodeLength = Object.values(json.Paths).reduce((acc, path) => acc + path.length, 0)
which will give you 6
Edit: since in the comment you said you needed to know how many elements are in your object, you can use
Object.keys(json.Paths).length
to get that
Related
I'm parsing an order feed to identify duplicate items bought and group them with a quantity for upload. However, when I try to map the resulting array, it's showing [object Object], which makes me think something's converting the return into an object rather than an array.
The function is as follows:
function compressedOrder (original) {
var compressed = [];
// make a copy of the input array
// first loop goes over every element
for (var i = 0; i < original.length; i++) {
var myCount = 1;
var a = new Object();
// loop over every element in the copy and see if it's the same
for (var w = i+1; w < original.length; w++) {
if (original[w] && original[i]) {
if (original[i].sku == original[w].sku) {
// increase amount of times duplicate is found
myCount++;
delete original[w];
}
}
}
if (original[i]) {
a.sku = original[i].sku;
a.price = original[i].price;
a.qtty = myCount;
compressed.push(a);
}
}
return compressed;
}
And the JS code calling that function is:
contents: compressedOrder(item.lineItems).map(indiv => ({
"id": indiv.sku,
"price": indiv.price,
"quantity": indiv.qtty
}))
The result is:
contents: [ [Object], [Object], [Object], [Object] ]
When I JSON.stringify() the output, I can see that it's pulling the correct info from the function, but I can't figure out how to get the calling function to pull it as an array that can then be mapped rather than as an object.
The correct output, which sits within a much larger feed that gets uploaded, should look like this:
contents:
[{"id":"sku1","price":17.50,"quantity":2},{"id":"sku2","price":27.30,"quantity":3}]
{It's probably something dead simple and obvious, but I've been breaking my head over this (much larger) programme till 4am this morning, so my head's probably not in the right place}
Turns out the code was correct all along, but I was running into a limitation of the console itself. I was able to verify this by simply working with the hard-coded values, and then querying the nested array separately.
Thanks anyway for your help and input everyone.
contents: compressedOrder(item.lineItems).map(indiv => ({
"id": indiv.sku,
"price": indiv.price,
"quantity": indiv.qtty
}))
In the code above the compressedOrder fucntion returns an array of objects where each object has sku, price and qtty attribute.
Further you are using a map on this array and returning an object again which has attributes id, price and quantity.
What do you expect from this.
Not sure what exactly solution you need but I've read your question and the comments, It looks like you need array of arrays as response.
So If I've understood your requirement correctly and you could use lodash then following piece of code might help you:
const _ = require('lodash');
const resp = [{key1:"value1"}, {key2:"value2"}].map(t => _.pairs(t));
console.log(resp);
P.S. It is assumed that compressedOrder response looks like array of objects.
I am trying to get a kind of "leaderboard" from a list of numbers. I was thinking of making an array with all the numbers like this
var array = [];
for (a = 0; a < Object.keys(wallets.data).length; a++) { //var wallets = a JSON (parsed) response code from an API.
if (wallets.data[a].balance.amount > 0) {
array.push(wallets.data[a].balance.amount)
}
}
//Add some magic code here that sorts the array into descending numbers
This is a great option, however I need some other values to come with the numbers (one string). That's why I figured JSON would be a better option than an array.
I just have no idea how I would implement this.
I would like to get a json like this:
[
[
"ETH":
{
"balance":315
}
],
[
"BTC":
{
"balance":654
}
],
[
"LTC":
{
"balance":20
}
]
]
And then afterwards being able to call them sorted descending by balance something like this:
var jsonarray[0].balance = Highest number (654)
var jsonarray[1].balance = Second highest number (315)
var jsonarray[2].balance = Third highest number (20)
If any of you could help me out or point me in the right direction I would appreciate it greatly.
PS: I need this to happen in RAW JS without any html or libraries.
You should sort the objects before making them a JSON. You can write your own function or use a lambda. See this [https://stackoverflow.com/questions/1129216/sort-array-of-objects-by-string-property-value]
Since you are dealing with cryptocurrency you can use the currency-code as a unique identifier.
Instead of an array, you can define an object with the currency as properties like this:
const coins = {
ETH: [300, 200, 500],
BTC: [20000, 15000, 17000]
}
then you can access each one and use Math.max or Math.min to grab the highest / lowest value of that hashmap. E.G. Math.max(coins.BTC)
And if you need to iterate over the coins you have Object.keys:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
Thank you all for your answer. I ended up using something like:
leaderboard = []
for (a = 0; a < Object.keys(wallets.data).length; a++) {
if (wallets.data[a].balance.amount > 0) {
leaderboard.push({"currency":wallets.data[a].balance.currency, "price":accprice}) //accprice = variable which contains the value of the userhold coins of the current coin in EUR
}
}
console.log(leaderboard.sort(sort_by('price', true, parseInt)));
I have a multidimensional array which contains coordinates extracted from a back-end call, this is a screenshot of the structure:
I would like to swap those coordinates but I cannot know how to handle that. Thanks.
Many ways to accomplish what you're looking for. One approach is to loop through the structure until you reach the arrays you want to manipulate. In the snippet, I decided to make a function that took the original data and returns a new object. To 'swap' the contents of the arrays, I did a .splice(0) to make a copy of the array, then called .reverse() on it to switch the order.
The main challenge is working through the data structure - some fairly intuitive levels to the current structure you have (a coordinates object that contains a node called coordinates that is array - just a little confusing)
var dataFromTheServer = {
content: [
{
coordinates: {
coordinates: [
[17.25756,31.19192],
[15.1821, 40.87555],
[33.78433, 18.59314],
[17.25756,31.19192]
]
}
}
]
}
function swapEm(data){
var response = {};
if(data && data.content){
response.content = [{coordinates:{coordinates:[]}}];
for(var item in data.content){
if(data.content[item] && data.content[item].coordinates && data.content[item].coordinates.coordinates){
for(var coord in data.content[item].coordinates.coordinates){
response.content[0].coordinates.coordinates[coord] = data.content[item].coordinates.coordinates[coord].splice(0).reverse()
}
}
}
}
return response;
}
console.log(dataFromTheServer);
console.log(swapEm(dataFromTheServer))
I'm brand new to programming so I apologize if this is a simple question.
I had a unique practice problem that I'm not quite sure how to solve:
I'm dealing with two arrays, both arrays are pulled from HTML elements on the page, one array is representing a bunch of states, and the next array is representing their populations. The point of the problem is to print the name of the states and their less than average populations.
To find and print all of the populations that are less than the average I used this code:
function code6() {
// clears screen.
clr();
// both variables pull data from HTML elements with functions.
var pop = getData2();
var states = getData();
var sum = 0;
for( var i = 0; i < pop.length; i++ ){
sum += parseInt( pop[i], 10 );
var avg = sum/pop.length;
if (pop[i] < avg) {
println(pop[i]);
// other functions used in the code to get data, print, and clear the screen.
function getData() {
var dataSource = getElement("states");
var numberArray = dataSource.value.split('\n');
// Nothing to split returns ['']
if (numberArray[0].length > 0) {
return(numberArray);
} else {
return [];
}
}
// Get the data from second data column
function getData2() {
var dataSource = getElement("pops");
var numberArray = dataSource.value.split('\n');
// Nothing to split returns ['']
if (numberArray[0].length > 0) {
return(numberArray);
} else {
return [];
}
}
// Clear the 'output' text area
function clr() {
var out = getElement("output");
out.value = "";
}
// Print to the 'output' HTML element and ADDS the line break
function println(x) {
if (arguments.length === 0) x = '';
print(x + '\n');
}
Now I just need to know how to get the value of these positions within the array so I can pull out the same positions from my states array and display them both side by side. Both arrays have the identical amount of items.
I hope this makes sense and thanks in advance to anyone who has time to take a look at this.
Best regards,
-E
Its a little hard to tell what you are trying to accomplish, but I guess you are going for something like:
'use strict'
function code6() {
const populations = ['39000000', '28000000', '21000000'];
const stateNames = ['california', 'texas', 'florida'];
const states = populations.map((population, i) => ({
'name': stateNames[i],
'population': Number(population),
}));
const sum = states.reduce((sum, state) => sum + state.population, 0);
const average = sum / populations.length;
states
.filter(state => state.population < average)
.forEach(state => {
const name = state.name;
const population = state.population;
console.log(`state name: ${name}, population: ${population}`);
});
}
// run the code
code6();
// state name: texas, population: 28000000
// state name: florida, population: 21000000
I took the liberty of refactoring your code to be a little more modern (es6) and Idiomatic. I hope its not to confusing for you. Feel free to ask any questions about it.
In short you should use:
'use strict' at the top of your files
const/let
use map/filter/forEach/reduce to iterate lists.
use meaningfull names
, and you should avoid:
classic indexed for-loop
parseInt
, and pretty much never ever use:
var
If your states array is built with corresponding indices to your pop one, like this:
states; //=> ['Alabama', 'Alaska', 'Arizona', ...]
pop; //=> [4863300, 741894, 6931071, ...]
then you could simply update your print statement to take that into account:
if (pop[i] < avg) {
println(state[i] + ': ' + pop[i]);
}
Or some such.
However, working with shared indices can be a very fragile way to use data. Could you rethink your getData and getData2 functions and combine them into one that returns a structure more like this the following?
states; //=> [
// {name: 'Alabama', pop: 4863300}
// {name: 'Alaska', pop: 741894},
// {name: 'Arizona', pop: 6931071},
// ...]
This would entail changes to the code above to work with the pop property of these objects, but it's probably more robust.
If your pop and state looks like:
var state = ['state1', 'state2', ...];
var pop = ['state1 pop', 'state2 pop', ...];
Then first of all, avg is already wrong. sum's value is running along with the loop turning avg's formula into sum as of iteration / array length instead of sum of all pops / array length. You should calculate the average beforehand. array.reduce will be your friend.
var average = pop.reduce(function(sum, val){return sum + val;}, 0) / pop.length;
Now for your filter operation, you can:
Zip up both arrays to one array using array.map.
Filter the resulting array with array.filter.
Finally, loop through the resulting array using array.forEach
Here's sample code:
var states = ['Alabama', 'Alaska'];
var pop = [4863300, 741894];
var average = pop.reduce(function(sum, val){return sum + val;}) / pop.length;
console.log('Average: ' + average);
states.map(function(state, index) {
// Convert 2 arrays to an array of objects representing state info
return { name: state, population: pop[index] };
}).filter(function(stateInfo) {
console.log(stateInfo);
// Filter each item by returning true on items you want to include
return stateInfo.population < average;
}).forEach(function(stateInfo) {
// Lastly, loop through your results
console.log(stateInfo.name + ' has ' + stateInfo.population + ' people');
});
I have 2 Arrays and one is 2 dimensional and another is 1 dimensional. I need to compare both and need to store there common data in another array. I tried the below approach:-
tw.local.listtodisplayNW = new tw.object.listOf.listtodisplayNWBO();
//if(tw.local.SQLResults[0].rows.listLength >
// tw.local.virtualServers.listLength)
var k=0;
for (var i=0;i<tw.local.SQLResults[0].rows.listLength;i++)
{
log.info("Inside SQLResults loop - For RuntimeID: "
+tw.local.SQLResults[0].rows[i].data[3]);
for(var j=0;j<tw.local.virtualServers.listLength;j++)
{
log.info("Inside API loop - For RuntimeID: "
+tw.local.virtualServers[j].runtimeid);
if(tw.local.SQLResults[0].rows[i].data[3] ==
tw.local.virtualServers[j].runtimeid)
{
tw.local.listtodisplayNW[k] = new tw.object.listtodisplayNWBO();
tw.local.listtodisplayNW[k].vsysName =
tw.local.virtualServers[j].virtualSystemName;
tw.local.listtodisplayNW[k].vsysID =
tw.local.virtualServers[j].virtualSystemId;
tw.local.listtodisplayNW[k].serverName =
tw.local.virtualServers[j].serverName;
tw.local.listtodisplayNW[k].serverID =
tw.local.virtualServers[j].serverId;
tw.local.listtodisplayNW[k].runtimeID =
tw.local.virtualServers[j].runtimeid;
//tw.local.listtodisplayNW[k].IPAddress =
tw.local.virtualServers[j].nics[j].ipAddress;
log.info("VsysName:
"+tw.local.listtodisplayNW[k].vsysName+"RuntimeID:
"+tw.local.listtodisplayNW[k].runtimeID);
//tw.local.listtodisplayNW[k] = new
tw.object.listtodisplayNWBO();
tw.local.listtodisplayNW[k].currentSpeed =
tw.local.SQLResults[0].rows[i].data[5];
log.info("VsysName:
"+tw.local.listtodisplayNW[k].vsysName+"RuntimeID:
"+tw.local.listtodisplayNW[k].runtimeID+"CurrentSpeed:
"+tw.local.listtodisplayNW[k].currentSpeed);
if(tw.local.listtodisplayNW[k].currentSpeed != "100 Mbps")
{
tw.local.listtodisplayNW[k].desiredSpeed = "100 Mbps";
}
else
{
tw.local.listtodisplayNW[k].desiredSpeed = "1 Gbps";
}
log.info("DesiredSpeed:
"+tw.local.listtodisplayNW[k].desiredSpeed);
k++;
}
}
log.info("Length of
listtodisplayNW"+tw.local.listtodisplayNW.listLength);
}
In above code SQLResults is a 2-d array and virtualServers is a 1-D array.
I need to compare both these array and common data need to be store in another array. Here performance is not good. Is there any other way to do this efficiently. Please make a needful favour and Thanks in advance.
Assuming integer data, the following example works on the theme of array implementation of set intersection, which will take care of performance.
Convert 2D array to 1D.
var 2DtoIDArray = 2DArray.join().split(",");
Create an array named marker whose purpose is to serve as a lookup that element.
This needs to be done as follows.
Iterate through the smaller array, say 1DArray and keep setting marker as follows throughout iteration.
marker[1DArray[counter]]='S1';
Now iterate through 2Dto1DArray array(you may use nested loop iteration if you dont want to convert it to 1 dimesnional) and for each element
of this array check if its marked as 'S1' in the marker lookup array.
If yes, keep adding the elements in the commonElementsArray.
Follow this simple approach
Since the matching condition is only one between the two large arrays, create two maps (one for each array) to map each record against that attribute which is to be matched
For SQLResults
var map1 = {};
tw.local.SQLResults[0].rows.each( function(row){
map1[ row.data[3] ] = row;
});
and similarly for virtual servers
var map2 = {};
tw.local.virtualServers.each( function(vs){
map2[ vs.runtimeid ] = vs;
});
Now iterate these two maps wrt to their keys and set the values in new array
new array being tw.local.listtodisplayNW
tw.local.listtodisplayNW = [];
Object.keys( map1 ).forEach( function( key ){
if( map2[ key ] )
{
//set the values in tw.local.listtodisplayNW
}
})
Complexity of the approach is simply O(n) since there is no nested loops.