How to select data

Question

I have below code to display chart

        d3.json("dat.csv", function(error, data) {


        Data.forEach(function(d) {

            d.Data = parseDate(d.Data);
            d.Free = +d.Free;

        });

This is picking data form all hosts , I want to restrict it to pick data. field will have all host names. how to put a check the data? please help

Answer 1

You can filter your data after receiving the d3.json response. I created a new variable (host1Data) for clarity:

d3.json("dat.json", function(error, data) {

    var host1Data = data.filter(function(d){
                        return d.host.name === 'host1';
                    });

    host1Data.forEach(function(d) {

        d.Date.Time = parseDate(d.Date.Time);
        d.CPU.Free = +d.CPU.Free;

    });

    // Use host1Data instead of data in the rest of your code
});

Alternatively, you can also filter the data when passing it to svg using javascript's filter function:

var mychart = svg.selectAll(".mychart")
  .data(data.filter(function(d){return d.host.name === 'host1'})
.enter().append("g")
  .attr("class", "mychart");

Or using d3's filter function:

var mychart = svg.selectAll(".mychart")
  .data(data)
.enter().append("g")
  .filter(function(d){return d.host.name === 'host1'}
  .attr("class", "mychart");