Accessing min and max value within JSON array in JavaScript/HTML

Question

I have the following code that gets data from a database and plots a graph using HTML and the FusionCharts library. I'm just having some trouble with the graph formatting. I want the yAxisMin to be 10 values below the minimum value in the data array and the yAxisMax value to be 10 values above.

function createJSON(name, data){
    return(
        {
            "chart": {
                "caption": String(name),
                "subCaption": "15-Day Prices",
                "xAxisName": "Day",
                "yAxisName": "Price (USD)",
                "anchorRadius": "1",
                "showValues": "0",
                "borderThickness": "3",
                "yAxisMinValue": data.value.min() - 10,
                "yAxisMaxValue": data.value.max() + 10,
                "theme": "fint"
            },
            "data": data,
        }
    );
}

//I'm including this for context. This is the function that returns the data array
var getHistory = function(req,res,next){

    var data = [];
    History.findOne({"Symbol": String(req.params.sym)}, function(err, foundHistory){
        if(foundHistory){
            (foundHistory.Historical).forEach(function(day){
                data.push({
                    "label": day.Date,
                    "value": day.Close
                });
            });
            res.json(createJSON(foundHistory.Name, data));
            next();
        }
        else{
            next();
        }
    }); 
};


module.exports = getHistory;

Everything else works fine. I just need help with the two lines of code:

"yAxisMinValue": data.value.min() - 10,
"yAxisMaxValue": data.value.max() + 10,

How would I do this? This was my attempt but it does not compile.

Sangbok Lee · Accepted Answer · 2017-04-01 18:46:07Z

1

How about this? Since your code sample is incomplete, I cannot test it myself.

function createJSON(name, data){
  var min = Number.MAX_SAFE_INTEGER;
  var max = Number.MIN_SAFE_INTEGER;
  for(var i = 0; i < data.length; i++) {
    if(data[i].value < min) min = data[i].value;
    if(data[i].value > max) max = data[i].value;
  }
  ...
      "yAxisMinValue": min - 10,
      "yAxisMaxValue": max + 10,
  ...

edited Apr 1, 2017 at 18:46

answered Apr 1, 2017 at 18:35

Sangbok Lee

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4 Comments

ss1111 Over a year ago

Still gives me an error but thank you for the help! I'll try to find the error

Sangbok Lee Over a year ago

What is the desired output and actual output? 'max does not' says nothing. I updated the code a few times. Please check again.

ss1111 Over a year ago

Min value is 110 and the graph min-y-value is correctly adjusting to 100. The max value is 150 but the graph just displays 150 instead of 160.

Sangbok Lee Over a year ago

Let us continue this discussion in chat.

CynicalBusiness · Accepted Answer · 2017-04-01 18:44:30Z

0

For 1-Dimensional Array of Numbers:

JavaScript's Math.max and Math.min will find the maximum or minimum of their arguments respectively, so, using an apply call, we can apply the array of numbers to these functions.

var values = [ 1, 2, 3, 4, 5 ]
Math.max.apply(null, values) // 5
Math.min.apply(null, values) // 1

For Anything Else:

If you want the index of the maximum or are comparing non-numeric values, a custom iterator is needed.

function getMax (values) 
  var maxIndex = -1
  var max = Number.MIN_VALUE // use Number.MAX_VALUE for min

  for (var i = 0; i < values.length; i++) {
    if (value[i] > max) { // do your "greater than" comparison here
      maxIndex = i
      max = value[i]
    }
  }

  // return what it is you need, max or maxIndex
  return max
end

edited Apr 1, 2017 at 18:44

answered Apr 1, 2017 at 18:27

CynicalBusiness

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3 Comments

ss1111 Over a year ago

Does it matter that my array is 2 dimensional? I don't think this would work in that case

CynicalBusiness Over a year ago

In that case, no. You would have to iterate over the array in question, storing the index (or the value itself) of the max/min. I will edit the answer to have this option as well.

Sangbok Lee Over a year ago

This way too, to get min and max takes two loops, which can be done in just one loop.

5ka · Accepted Answer · 2017-04-01 18:44:31Z

0

Try something like that:

  "yAxisMinValue": getMinValue(data) - 10,
    "yAxisMaxValue": getMaxValue(data) + 10,   


 function getMinValue(data)
     {
       var min = Number.MAX_VALUE;
        for (var key in data)
         {
           if(data[key].value < min)
            {
               min = data[key].value;
            }
         }
        return min;
     }


 function getMaxValue(data)
     {
       var max = Number.MIN_VALUE;
        for (var key in data)
         {
           if(data[key].value > max)
            {
               max = data[key].value;
            }
         }
        return max;
     }

edited Apr 1, 2017 at 18:44

answered Apr 1, 2017 at 18:27

5ka

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7 Comments

5ka Over a year ago

Idk what type is day.Close. If it isnt numeric, you have to check min in other way.

ss1111 Over a year ago

day.Close is a floating point number. I tried running this function and it returns -9999 + or - 10.

Sangbok Lee Over a year ago

Obviously, no max calculation here.

5ka Over a year ago

Max has the same logic.

ss1111 Over a year ago

I tried this out and it works! Only thing is, the max value + 10 is returning just the max value and I can't seem to find the error

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