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How do I access the array sum here?

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-上瘾入骨i
-上瘾入骨i 2021-01-21 00:37

I have a data set that looks roughly like this:

var dataset = [
  // apples
  [{\"x\": 1, \"y\": 5 }, { \"x\": 2, \"y\": 4 }, { \"x\": 3, \"y\": 2 }, { \"x\": 4,
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2条回答
  • 青春惊慌失措
    2021-01-21 00:55

    d3.zip() comes in handy here, since you're manipulating data based on array index.

    https://jsfiddle.net/guanzo/o8voyydx/2/

    var result = dataset.map(d=>d.map(d=>d.y))
result = d3.zip.apply(undefined,result)
result = d3.max(result.map(d=>d3.sum(d)))
console.log(result )//83
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  • 野性不改
    2021-01-21 01:01

    Here's a horrifying solution and as close to a "one-liner" as I can get. It'll handle un-even length arrays too:

    <!DOCTYPE html>
<html>

<head>
  <script data-require="d3@3.5.3" data-semver="3.5.3" src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.js"></script>
</head>

<body>
  <script>
    var dataset = [
      // apples
      [{
        "x": 1,
        "y": 5
      }, {
        "x": 2,
        "y": 4
      }, {
        "x": 3,
        "y": 2
      }, {
        "x": 4,
        "y": 7
      }, {
        "x": 5,
        "y": 23
      }],
      // oranges
      [{
        "x": 1,
        "y": 10
      }, {
        "x": 2,
        "y": 12
      }, {
        "x": 3,
        "y": 19
      }, {
        "x": 4,
        "y": 23
      }, {
        "x": 5,
        "y": 17
      }],
      // grapes
      [{
        "x": 1,
        "y": 22
      }, {
        "x": 2,
        "y": 28
      }, {
        "x": 3,
        "y": 32
      }, {
        "x": 4,
        "y": 35
      }, {
        "x": 5,
        "y": 43
      }]
    ];
  
   var l = d3.max(dataset, function(d){
     return d.length;
   }), 
   sumArr = d3.range(l).map(function(i){
     return dataset.map(function(d){
       return d[i] ? d[i].y : 0;
     });
   }).map(function(d){
     return d3.sum(d);
   });
   
  d3.select("body").text(sumArr);
    
  </script>
</body>

</html>

    P.S. Eric's solution is so much better...

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