Is there any way of knowing what constraints is a body attached to? I want to create a constraint each time two bodies collide, but not each time they collide after that first constraint is already created
UPDATE: Added proof of concept
In my code, i create an array of pairs with duplicate values, and because i have a maximum of 1000 elements, each value is duplicated in x+y1000 and y+x1000 indexes so they won't overlay
// global array
var alreadyPaired = [];
// on collision check, i save which pair of values must be paired
Matter.Events.on(engine, 'collisionStart', function(event) {
var idA = event.pairs[i].bodyA.id;
var idB = event.pairs[i].bodyB.id;
if ( !alreadyPaired[idA*1000+idB] && !alreadyPaired[idB*1000+idA] ) {
alreadyPaired[idA*1000+idB] = true;
alreadyPaired[idB*1000+idA] = true;
}
});
Related
the function .map applies a function to every individual image in an ImageCollection. And the function .iterate applies a function to one image and the output of the calculation done to the precedent image on an ImageCollection.
The first only works with one image each time, and the second implies modifying each image and utilize it to any calculation with the next one.
I need a function that works like .iterate, but does not modify the precedent image. I just need to do:
image (time -1) / image (time 0).
I can not find a way to do it,
thanks for your help
i have tried,
var first = ee.List([
ee.Image(1).set('system:time_start', time0).select([0], ['pc1'])
]);
var changeDET = function(image, list) {
var previous = ee.Image(ee.List(list).get(-1));
var change = previous.divide(image.select('pc1'))
.set('system:time_start', image.get('system:time_start'));
return ee.List(list).add(change);
};
var cumulative = ee.ImageCollection(ee.List(imageCollection.iterate(changeDET, first)))
.sort('system:time_start', false)
What you can do is to convert your imageCollection into a ee.List object, then map over that list with an index variable to access the previous image. Example code is below:
var length = yourImageCollection.size();
var list = yourImageCollection.toList(length);
var calculated_list = list.map(function(img) {
var index = list.indexOf(img)
img = ee.Image(img);
var previousIndex = ee.Algorithms.If(index.eq(0), index, index.subtract(1));
var previousImage = ee.Image(list.get(previousIndex)):
var change = ee.Image(previousImage.divide(img)
.copyProperties(img, ["system:time_start"]));
return change;
})
I'm not sure what you want to do with the first image, so when map function reach the first image, previousIndex will equal to index. In other words, the first image will be divided by itself (as there is no image before it).
Hope this helps.
I have table with multiple customerKey values assigned to a numeric value; I wrote a script where foreach row of data I scan whole table to find all values assigned to the current customerKey and return a highest one;
I have a problem with performance - script processes around 10 records per second - any ideas how to improve this or maybe propose an alternative solution plesae?
function getLastest() {
var date = app.models.magicMain.newQuery();
var date_all = date.run();
date_all.forEach(function(e) { // for every row of date_all
var temp = date_all.filter(function(x) {
return x.SubscriberKey === e.SubscriberKey; // find matching records for the current x.SubscriberKey
});
var dates = [];
temp.forEach(function(z) { // get all matching "dates"
dates.push(z.Date);
});
var finalValue = dates.reduce(function(a, b) { // get highest dates value (integer)
return Math.max(a, b);
});
var record = app.models.TempOperatoins.newRecord(); // save results to DB
record.email = e.SubscriberKey.toString() + " " + finalValue.toString();
app.saveRecords([record]);
});
}
The only suggestion I have would be to add:
var recordstosave = [];
At the top of your function.
Then replace app.saveRecords([record]) with recordstosave.push(record).
Finally outside of your foreach function do app.saveRecords(recordstosave).
I saw major processing time improvements doing this rather than saving each record individually inside a loop.
I have some json, for examle:
data = {
"name":"Bob","age":"20",
"name":"Jo","age":"21",
"name":"Jo","age":"22",
"name":"Nick","age":"23"
}
Next, I use crossfilter, create dimension and filter it:
let ndx = crossfilter(data);
let dim = ndx.dimension(d => d.name).filter(d !== "Jo");
//try to get filtered values
let filtered = dim.top(Infinity); // -> return 2 values where 'name'!='Jo'
//"name":"Bob","age":"20"
//"name":"Nick","age":"23"
let myGroup = dim.group(d => {
if(d === 'Jo') {
//Why we come here? This values must be filtered already
}
})
How can I filter my dimension and don't have these values on 'dim.group'?
Not sure what version you are using, but in the current version of Crossfilter, when a new group is created all records are first added to the group and then filtered records are removed. So the group accessor will be run at least once for all records.
Why do we do this? Because for certain types of grouping logic, it is important for the group to "see" a full picture of all records that are in scope.
It is possible that the group accessor is run over all records (even filtered ones) anyway in order to build the group index, but I don't remember.
In my project, I must know first and last key of child to do something. I have query same below, I use 'i' to find first but I don't know how to get last key? Have any ways to set if Firebase query complete will do function with child_added? .In test, console.log(last) but is undefinded
var i = 0;
myDataRef.limitToLast(10).on('child_added', function (snapshot){
if( i == 0)
{
first = snapshot.key;
}
renderInfo(snapshot.key, snapshot.val(), 'new');
last = snapshot.key;
});
console.log(last)
What I need to do is use either collection-2 or another package to automatically create a new order number, incremented from the last order number used.
i.e. Starting off with PO123456, when I save this order, the next time I make a new PO, it automatically generates the number PO123457.
I've been looking for a good example or tutorial, but I'm not able to find one.
Using konecty:mongo-counter in conjuntion with aldeed:collection2 and aldeed:simple-schema should be pretty straightforward. In your schema definition try:
POnumber: { type: String, autoValue: function(){
if ( this.isInsert ){ // restrict to when inserting a document
var currentNumber = incrementCounter('purchase order'); // this will use mongo-counter
// WARNING: you can only ever get as rich as 10M POs!!
var zeroPad = "000000" + currentNumber; // pad with 6 zeros
zeroPad = zeroPad.substr(zeroPad.length-7); // restrict to 7 places
return 'PO' + zeroPad; // prefix with 'PO'
} else if ( this.isSet ){
this.unset(); // prevent attempts to change the number
}
}