Question

I have lists of values as seen below:

function(obj){

  var props = Object.keys(obj), p = Promise.resolve();
  props.forEach(function(prop){
    p = p.then(function(){
      if(condition){ // can access obj[prop] and obj here
        obj.children = example.getData(...); // getData returns a promise
        return obj.children; // return the promise.
      }
    });
});

Promise.resolve(obj.children).then(function(children){
    // here the async call to get `.children` is done.
    // can wait for `p` too (the loop) if we care about it
    if(obj.length === 10) // do stuff
});

I obtain the list above by using the append within a for loop where Mw_Price is Mw(51) and Price(4889.37) for each iteration

[(51, 4889.37), (58, 5582.51), (62, 6005.07), (67, 6533.27)]

Is there an append to a dict?

I need my output to be as such:

 new_list.append(Mw_Price)

Answer 1

From your rough description of your code (please include actual code for best answers), you can probably do something like:

SELECT num, SUM(amount) AS total
FROM amounts LEFT JOIN numbers ON amounts.nr=numbers.num
GROUP BY num;

to get the result you want.

Answer 2

You'd probably better unpack the pairs into two separate variables in the first place:

this._worker = new Worker( Physijs.scripts.worker || 'physijs_worker.js' );

Or if you insist on loop-and-append:

old_list = [(51, 4889.37), (58, 5582.51), (62, 6005.07), (67, 6533.27)]
new_list = [{'Mw': mw, 'Price': price} for mw, price in old_list]

Create a dict from a list that contains no keys

2 个答案: