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How do I pick out the data of the selected area after an 'axisZoom' event for a candlestick
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ddsmith
#1 Posted : Monday, March 10, 2014 3:14:39 PM(UTC)
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EDIT:
I am looking to find the min/max range of the high/low values of a selected area of a candle stick chart.

Similar to the zoom feature that selects an area.

How do I pick out the data of the selected area?

Or, How to convert actualVisibleMinimum/actualVisibleMaximum to a data index after an 'axisZoom' event?

They appear to be scaled date values.

I need the data values (high,low,open,close) at the minX and maxX dates locations returned by the axisZoom event.

$('#chartCandle1a').bind('axisZoom', function (e, data) {
var axis = data.axis;
var minX = axis.actualVisibleMinimum;
var maxX = axis.actualVisibleMaximum;

// convert minX and maxX to an index into data on a candle stick chart
}
});
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Dragan
#2 Posted : Tuesday, March 11, 2014 7:02:37 AM(UTC)
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Hi,

You can use the following code to get the visible candlestick data:

Code:
var chartData = []; // candlestick data

            $('#chartCandle1a').bind('axisZoom', function (e, data) {
                var axis = data.axis;
                var minX = axis.actualVisibleMinimum;
                var maxX = axis.actualVisibleMaximum;

                var visibleData = [];

                for (var i = 0; i < chartData.length; i++) {

                    var dataItem = chartData[i];
                    var date = dataItem[0];

                    if (data >= minX && data <= maxX) {
                        visibleData.push(dataItem);
                    }
                }
            });
Best Regards,
Dragan Matek
jqChart Inc.
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ddsmith
#3 Posted : Tuesday, March 11, 2014 7:58:41 PM(UTC)
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This does not work, the vars actualVisibleMinimum and actualVisibleMaximum are doubles not dates.
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Dragan
#4 Posted : Wednesday, March 12, 2014 3:46:32 AM(UTC)
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Sorry, you can change it to:

Code:
var chartData = []; // candlestick data

            $('#chartCandle1a').bind('axisZoom', function (e, data) {
                var axis = data.axis;
                var minX = axis.actualVisibleMinimum;
                var maxX = axis.actualVisibleMaximum;

                var visibleData = [];

                for (var i = 0; i < chartData.length; i++) {

                    var dataItem = chartData[i];
                    var date = dataItem[0.getTime();

                    if (data >= minX && data <= maxX) {
                        visibleData.push(dataItem);
                    }
                }
            });
Best Regards,
Dragan Matek
jqChart Inc.
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ddsmith
#5 Posted : Wednesday, March 12, 2014 12:13:46 PM(UTC)
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Code:
Dragan,

This is better but axis.actualVisibleMinimum and axis.actualVisibleMaximum do not point to the cursor locations.

The candle stick chart does display correctly when zoomed the dates pointed to by axis.actualVisibleMinimum and axis.actualVisibleMaximum are not the same as the selected points.

Here is my code

Code:
    var candleDataBASE = [
        ['2014-03-11', 188.71, 186.8, 188.44, 187.23],
        ['2014-03-10', 188.23, 187.08, 187.97, 188.16],
        ['2014-03-07', 188.96, 187.43, 188.96, 188.26],
        ['2014-03-06', 188.61, 187.78, 188.21, 188.18],
        ['2014-03-05', 188.07, 187.45, 187.74, 187.75],
        ['2014-03-04', 187.98, 186.75, 186.79, 187.58],
        ['2014-03-03', 185.45, 183.75, 184.65, 184.98],
        ['2014-02-28', 187.15, 185.05, 185.79, 186.29],
        ['2014-02-27', 185.87, 184.37, 184.58, 185.82],
        ['2014-02-26', 185.6, 184.33, 185.11, 184.85],
        ['2014-02-25', 185.59, 184.23, 185.06, 184.84],
        ['2014-02-24', 186.15, 184.2, 184.28, 184.91],
        ['2014-02-21', 184.89, 183.8, 184.45, 183.89],
        ['2014-02-20', 184.52, 182.6, 183.27, 184.1],
        ['2014-02-19', 184.95, 182.87, 183.76, 183.02],
        ['2014-02-18', 184.49, 183.65, 184.18, 184.24],
        ['2014-02-14', 184.36, 182.67, 182.84, 184.02],
        ['2014-02-13', 183.2, 180.83, 180.84, 183.01],
        ['2014-02-12', 182.83, 181.71, 182.25, 182.07],
        ['2014-02-11', 182.44, 180.04, 180.16, 181.98],
        ['2014-02-10', 180.07, 179.21, 179.7, 180.01],
        ['2014-02-07', 179.87, 177.73, 178.31, 179.68],
        ['2014-02-06', 177.48, 175.22, 175.58, 177.48],
        ['2014-02-05', 175.56, 173.71, 174.78, 175.17],
        ['2014-02-04', 175.84, 174.11, 174.95, 175.39],
        ['2014-02-03', 178.37, 173.83, 177.97, 174.17]
    ];

    function parseDate(date) {
        var items = date.split('-');
        var yr = parseInt(items[0]);
        var mn = parseInt(items[1]);
        var da = parseInt(items[2]);
        var theDate = new Date(parseInt(items[0]), parseInt(items[1]) - 1, parseInt(items[2]));
        return new Date(parseInt(items[0]), parseInt(items[1]) - 1, parseInt(items[2]));
    }

    function drawCandle() {
        for (var i = 0; i < candleDataBASE.length; i++) {
            var date = parseDate(candleDataBASE[i][0]); // convert string to date structure
            var high = candleDataBASE[i][1];
            var low = candleDataBASE[i][2];
            var open = candleDataBASE[i][3];
            var close = candleDataBASE[i][4];
            candleData.push([date, high, low, open, close]);
        }

        $('#chartCandle').jqChart({
            legend: { visible: false },
            height: 512,
            grid: { drawGridlines: true },
            crosshairs: { snapToDataPoints: true, enabled: true, vLine: { strokeStyle: '#cc0a0c' } },
            axes: [{ type: 'linear', location: 'left', zoomEnabled: false, width: 50, labels: { stringFormat: '$%d', font: '12px sans-serif' } },
                   { type: 'dateTime', location: 'bottom', skipEmptyDays: true, zoomEnabled: true }],
            series: [{ type: 'candlestick', data: candleData, priceUpFillStyle: 'green', priceDownFillStyle: 'red', strokeStyle: 'black' }]
        });
    }

    $('#chartCandle').bind('axisZoom', function (e, data) {
        var axis = data.axis;
        var chart = $('#chartCandle').jqChart('chart');
        var minX = axis.actualVisibleMinimum;
        var maxX = axis.actualVisibleMaximum;

        var highMark = -99999;
        var lowMark = 99999;
        var series = chart.series.items[0];
        var highDateSelected;
        var lowDateSelected;

        var minMark = 99999999999999999;
        var maxMark = 99999999999999999;
        var minDate;
        var maxDate;

        for (var i = 0; i < candleData.length; i++) {
            var dataItem = candleData[i];
            var xVal = dataItem[0].getTime();

            var a1 = Math.abs(xVal - minX);
            if (a1 < minMark) {
                minMark = a1;
                minDate = dataItem[0].toDateString();
            }
            var a2 = Math.abs(maxX - xVal);
            if (a2 < maxMark) {
                maxMark = a2;
                maxDate = dataItem[0].toDateString();
            }
            if (xVal >= minX && xVal <= maxX) {
                if (dataItem[1] > highMark) {
                    highMark = dataItem[1];
                }
                if (dataItem[2] < lowMark) {
                    lowMark = dataItem[2];
                }
            }
        }
    });
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Dragan
#6 Posted : Thursday, March 13, 2014 7:41:42 AM(UTC)
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It seems that when skipEmptyDays is set to true, the intervals have some offsets.

If you change these lines:
Code:
$('#chartCandle').bind('axisZoom', function (e, data) {
        var axis = data.axis;
        var chart = $('#chartCandle').jqChart('chart');
        var minX = axis.actualVisibleMinimum;
        var maxX = axis.actualVisibleMaximum;

to
Code:
  $('#chartCandle').bind('axisZoom', function (e, data) {

                var axis = data.axis;
                var chart = $('#chartCandle').jqChart('chart');
                var minX = axis._addEmptyDaysOffset(axis.actualVisibleMinimum);
                var maxX = axis._addEmptyDaysOffset(axis.actualVisibleMaximum);

the visible range will be correct.
Best Regards,
Dragan Matek
jqChart Inc.
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1 user thanked Dragan for this useful post.
ddsmith on 3/13/2014(UTC)
ddsmith
#7 Posted : Thursday, March 13, 2014 7:58:39 AM(UTC)
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Dragan,

That is it! Thanks
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