d3intro_ex21

Intro d3js

### Example21 - join by key

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Intro d3js examples</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
    <style>
      body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
      p:hover {
        cursor: pointer;
      }
    </style>
  </head>
  <body>
    <h1>Intro d3js - example21</h1>
    <p id="add">Click here to add data</p>
    <p id="remove">Click here to remove data</p>
    
    <script type="text/javascript">
    	//Width and height
      var w = 600;
      var h = 250;
      var offset = 10;
      
      var dataset = [ { key: 0, value: 5 }, //dataset is now an array of objects.
              { key: 1, value: 10 },
              { key: 2, value: 13 },
              { key: 3, value: 19 },
              { key: 4, value: 21 },
              { key: 5, value: 25 },
              { key: 6, value: 22 },
              { key: 7, value: 18 },
              { key: 8, value: 15 },
              { key: 9, value: 13 },
              { key: 10, value: 11 },
              { key: 11, value: 12 },
              { key: 12, value: 15 },
              { key: 13, value: 20 },
              { key: 14, value: 18 },
              { key: 15, value: 17 },
              { key: 16, value: 16 },
              { key: 17, value: 18 },
              { key: 18, value: 23 },
              { key: 19, value: 25 } ];
      
      var xScale = d3.scale.ordinal()
              .domain(d3.range(dataset.length))
              .rangeRoundBands([0, w], 0.05);

var yScale = d3.scale.linear()
              .domain([0, d3.max(dataset, function(d) { return d.value; })])
              .range([h, 0]);
      
      //Define key function, to be used when binding data
      var key = function(d) {
        return d.key;
      };

//Create SVG element
      var svg = d3.select("body")
            .append("svg")
            .attr("width", w)
            .attr("height", h);

//Create bars
      svg.selectAll("rect")
         .data(dataset, key)
         .enter()
         .append("rect")
         .attr("x", function(d, i) {
             return xScale(i);
         })
         .attr("y", function(d) {
             return yScale(d.value);
         })
         .attr("width", xScale.rangeBand())
         .attr("height", function(d) {
             return h - yScale(d.value);
         })
         .attr("fill", function(d) {
          return "rgb(0, 0, " + (d.value * 10) + ")";
         });

//Create labels
      svg.selectAll("text")
         .data(dataset, key)
         .enter()
         .append("text")
         .text(function(d) {
             return d.value;
         })
         .attr("text-anchor", "middle")
         .attr("x", function(d, i) {
             return xScale(i) + xScale.rangeBand() / 2;
         })
         .attr("y", function(d) {
             return yScale(d.value) + offset;
         })
         .attr("font-family", "sans-serif")
         .attr("font-size", "11px")
         .attr("fill", "white");

//On click, update with new data      
      d3.selectAll("p")
        .on("click", function() {

//See which p was clicked
          var paragraphID = d3.select(this).attr("id");
          
          //Decide what to do next
          if (paragraphID == "add") {
            //Add a data value
            var maxValue = 25;
            var newNumber = Math.floor(Math.random() * maxValue);
            var lastKeyValue = dataset[dataset.length - 1].key;
            console.log(lastKeyValue);
            dataset.push({
              key: lastKeyValue + 1,
              value: newNumber
            });
          } 
        	else {
            //Remove a value
            dataset.shift();  //Remove one value from dataset
          }
          
          //Update scale domains
          xScale.domain(d3.range(dataset.length));
          yScale.domain([0, d3.max(dataset, function(d) { return d.value; })]);

//Select…
          var bars = svg.selectAll("rect")
            .data(dataset, key);
          
          //Enter…
          bars.enter()
            .append("rect")
            .attr("x", w)
            .attr("y", function(d) {
              return yScale(d.value);
            })
            .attr("width", xScale.rangeBand())
            .attr("height", function(d) {
              return h - yScale(d.value);
            })
            .attr("fill", function(d) {
              return "rgb(0, 0, " + (d.value * 10) + ")";
            });

//Update…
          bars.transition()
            .duration(500)
            .attr("x", function(d, i) {
              return xScale(i);
            })
            .attr("y", function(d) {
              return yScale(d.value);
            })
            .attr("width", xScale.rangeBand())
            .attr("height", function(d) {
              return h - yScale(d.value);
            });

//Exit…
          bars.exit()
            .transition()
            .duration(500)
            .attr("x", -xScale.rangeBand())
            .remove();

//Update all labels
  
          //Select…
          var labels = svg.selectAll("text")
            .data(dataset, key);
          
          //Enter…
          labels.enter()
            .append("text")
            .text(function(d) {
              return d.value;
            })
            .attr("text-anchor", "middle")
            .attr("x", w)
            .attr("y", function(d) {
              return yScale(d.value) + offset;
            })            
             .attr("font-family", "sans-serif")
             .attr("font-size", "11px")
             .attr("fill", "white");

//Update…
          labels.transition()
            .duration(500)
            .attr("x", function(d, i) {
              return xScale(i) + xScale.rangeBand() / 2;
            });

//Exit…
          labels.exit()
            .transition()
            .duration(500)
            .attr("x", -xScale.rangeBand())
            .remove();
        });
      </script>
  </body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js