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Brushable Horizontal Bar Chart - V

This is exactly the same as version IV of the brushable horizontal bar chart, but this one has a x scale that updates to fit the largest visible bar in the available width.

For a bit more background, you can read my mini-blog about it Brushable & interactive bar chart in d3.js

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <title>Brushable bar chart - Horizontal - V</title>

<link href='https://fonts.googleapis.com/css?family=Open+Sans:300,400' rel='stylesheet' type='text/css'>

<script src="//d3js.org/d3.v3.min.js"></script>

#title {
      font-size: 20px;
      padding-bottom: 10px;
      padding-top: 20px;
      font-weight: 300;
    }

#explanation {
      font-size: 12px;
      max-width: 620px;
      margin: 0 auto;
      padding-top: 10px;
      color: #ababab;
      font-weight: 300;
    }

.y.axis line {
      fill: none;
    }

.x.axis line {
      fill: none;
      stroke: #e0e0e0;
      shape-rendering: crispEdges;
    }

.axis path {
      display: none;
    }

.brush .extent {
      fill-opacity: .125;
      shape-rendering: crispEdges;
    }

.resize {
      display: inline !important; /* show when empty */
      fill: #7A7A7A;
      fill-opacity: 1;
      stroke: #7A7A7A;
      stroke-width: 2px;
    }

.bar {
      /*shape-rendering: crispEdges;*/
    }
  </style>

</head>

<body>

<div id="title">Brushable horizontal bar chart - V</div>
  <div id="chart"></div>
  <div id="explanation">You can see more or less of the total bar chart on the left by either dragging the box in the mini chart on the right or by scrolling your mouse. You can also click anywhere in the mini chart to center the box on that region. And you can increase and decrease the size of the box by dragging the top or bottom handle up or down.</div>

var data = [],
      svg,
      defs,
      gBrush,
      brush,
      main_xScale,
      mini_xScale,
      main_yScale,
      mini_yScale,
      main_yZoom,
      main_xAxis,
      main_yAxis,
      mini_width,
      textScale;

init();

function init() {

//Create the random data
    for (var i = 0; i < 40; i++) {
      var my_object = {};
      my_object.key = i;
      my_object.country = makeWord();
      my_object.value = Math.floor(Math.random() * 600);
      data.push(my_object);
    }//for i 
    data.sort(function(a,b) { return b.value - a.value; });

/////////////////////////////////////////////////////////////
    ///////////////// Set-up SVG and wrappers ///////////////////
    /////////////////////////////////////////////////////////////

//Added only for the mouse wheel
    var zoomer = d3.behavior.zoom()
        .on("zoom", null);

var main_margin = {top: 10, right: 10, bottom: 30, left: 100},
        main_width = 500 - main_margin.left - main_margin.right,
        main_height = 400 - main_margin.top - main_margin.bottom;

var mini_margin = {top: 10, right: 10, bottom: 30, left: 10},
        mini_height = 400 - mini_margin.top - mini_margin.bottom;
    mini_width = 100 - mini_margin.left - mini_margin.right;

svg = d3.select("#chart").append("svg")
        .attr("class", "svgWrapper")
        .attr("width", main_width + main_margin.left + main_margin.right + mini_width + mini_margin.left + mini_margin.right)
        .attr("height", main_height + main_margin.top + main_margin.bottom)
        .call(zoomer)
        .on("wheel.zoom", scroll)
        //.on("mousewheel.zoom", scroll)
        //.on("DOMMouseScroll.zoom", scroll)
        //.on("MozMousePixelScroll.zoom", scroll)
        //Is this needed?
        .on("mousedown.zoom", null)
        .on("touchstart.zoom", null)
        .on("touchmove.zoom", null)
        .on("touchend.zoom", null);

var mainGroup = svg.append("g")
            .attr("class","mainGroupWrapper")
            .attr("transform","translate(" + main_margin.left + "," + main_margin.top + ")")
            .append("g") //another one for the clip path - due to not wanting to clip the labels
            .attr("clip-path", "url(#clip)")
            .style("clip-path", "url(#clip)")
            .attr("class","mainGroup");

var miniGroup = svg.append("g")
            .attr("class","miniGroup")
            .attr("transform","translate(" + (main_margin.left + main_width + main_margin.right + mini_margin.left) + "," + mini_margin.top + ")");

var brushGroup = svg.append("g")
            .attr("class","brushGroup")
            .attr("transform","translate(" + (main_margin.left + main_width + main_margin.right + mini_margin.left) + "," + mini_margin.top + ")");

/////////////////////////////////////////////////////////////
    ////////////////////// Initiate scales //////////////////////
    /////////////////////////////////////////////////////////////

main_xScale = d3.scale.linear().range([0, main_width]);
    mini_xScale = d3.scale.linear().range([0, mini_width]);

main_yScale = d3.scale.ordinal().rangeBands([0, main_height], 0.4, 0);
    mini_yScale = d3.scale.ordinal().rangeBands([0, mini_height], 0.4, 0);

//Based on the idea from: https://stackoverflow.com/questions/21485339/d3-brushing-on-grouped-bar-chart
    main_yZoom = d3.scale.linear()
        .range([0, main_height])
        .domain([0, main_height]);

//Create x axis object
    main_xAxis = d3.svg.axis()
      .scale(main_xScale)
      .orient("bottom")
      .ticks(4)
      //.tickSize(0)
      .outerTickSize(0);

//Add group for the x axis
    d3.select(".mainGroupWrapper")
        .append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(" + 0 + "," + (main_height + 5) + ")");

//Create y axis object
    main_yAxis = d3.svg.axis()
      .scale(main_yScale)
      .orient("left")
      .tickSize(0)
      .outerTickSize(0);

//Add group for the y axis
    mainGroup.append("g")
        .attr("class", "y axis")
        .attr("transform", "translate(-5,0)");
 
    /////////////////////////////////////////////////////////////
    /////////////////////// Update scales ///////////////////////
    /////////////////////////////////////////////////////////////

//Update the scales
    main_xScale.domain([0, d3.max(data, function(d) { return d.value; })]);
    mini_xScale.domain([0, d3.max(data, function(d) { return d.value; })]);
    main_yScale.domain(data.map(function(d) { return d.country; }));
    mini_yScale.domain(data.map(function(d) { return d.country; }));
    
    //Create the visual part of the y axis
    d3.select(".mainGroup").select(".y.axis").call(main_yAxis);

/////////////////////////////////////////////////////////////
    ///////////////////// Label axis scales /////////////////////
    /////////////////////////////////////////////////////////////

textScale = d3.scale.linear()
      .domain([15,50])
      .range([12,6])
      .clamp(true);
    
    /////////////////////////////////////////////////////////////
    ///////////////////////// Create brush //////////////////////
    /////////////////////////////////////////////////////////////

//What should the first extent of the brush become - a bit arbitrary this
    var brushExtent = Math.max( 1, Math.min( 20, Math.round(data.length*0.2) ) );

brush = d3.svg.brush()
        .y(mini_yScale)
        .extent([mini_yScale(data[0].country), mini_yScale(data[brushExtent].country)])
        .on("brush", brushmove)
        //.on("brushend", brushend);

//Set up the visual part of the brush
    gBrush = d3.select(".brushGroup").append("g")
      .attr("class", "brush")
      .call(brush);
    
    gBrush.selectAll(".resize")
      .append("line")
      .attr("x2", mini_width);

gBrush.selectAll(".resize")
      .append("path")
      .attr("d", d3.svg.symbol().type("triangle-up").size(20))
      .attr("transform", function(d,i) { 
        return i ? "translate(" + (mini_width/2) + "," + 4 + ") rotate(180)" : "translate(" + (mini_width/2) + "," + -4 + ") rotate(0)"; 
      });

gBrush.selectAll("rect")
      .attr("width", mini_width);

//On a click recenter the brush window
    gBrush.select(".background")
      .on("mousedown.brush", brushcenter)
      .on("touchstart.brush", brushcenter);

///////////////////////////////////////////////////////////////////////////
    /////////////////// Create a rainbow gradient - for fun ///////////////////
    ///////////////////////////////////////////////////////////////////////////

defs = svg.append("defs")

//Create two separate gradients for the main and mini bar - just because it looks fun
    createGradient("gradient-rainbow-main", "60%");
    createGradient("gradient-rainbow-mini", "13%");

//Add the clip path for the main bar chart
    defs.append("clipPath")
      .attr("id", "clip")
      .append("rect")
    	.attr("x", -main_margin.left)
      .attr("width", main_width + main_margin.left)
      .attr("height", main_height);

/////////////////////////////////////////////////////////////
    /////////////// Set-up the mini bar chart ///////////////////
    /////////////////////////////////////////////////////////////

//The mini brushable bar
    //DATA JOIN
    var mini_bar = d3.select(".miniGroup").selectAll(".bar")
      .data(data, function(d) { return d.key; });

//UDPATE
    mini_bar
      .attr("width", function(d) { return mini_xScale(d.value); })
      .attr("y", function(d,i) { return mini_yScale(d.country); })
      .attr("height", mini_yScale.rangeBand());

//ENTER
    mini_bar.enter().append("rect")
      .attr("class", "bar")
      .attr("x", 0)
      .attr("width", function(d) { return mini_xScale(d.value); })
      .attr("y", function(d,i) { return mini_yScale(d.country); })
      .attr("height", mini_yScale.rangeBand())
      .style("fill", "url(#gradient-rainbow-mini)");

//EXIT
    mini_bar.exit()
      .remove();

//Start the brush
    gBrush.call(brush.event);

}//init

//Function runs on a brush move - to update the big bar chart
  function update() {

/////////////////////////////////////////////////////////////
    ////////// Update the bars of the main bar chart ////////////
    /////////////////////////////////////////////////////////////

//DATA JOIN
    var bar = d3.select(".mainGroup").selectAll(".bar")
        .data(data, function(d) { return d.key; });

//UPDATE
    bar
      .attr("y", function(d,i) { return main_yScale(d.country); })
      .attr("height", main_yScale.rangeBand())
      .attr("x", 0)
      .transition().duration(50)
      .attr("width", function(d) { return main_xScale(d.value); });

//ENTER
    bar.enter().append("rect")
      .attr("class", "bar")
      .style("fill", "url(#gradient-rainbow-main)")
      .attr("y", function(d,i) { return main_yScale(d.country); })
      .attr("height", main_yScale.rangeBand())
      .attr("x", 0)
      .transition().duration(50)
      .attr("width", function(d) { return main_xScale(d.value); });

//EXIT
    bar.exit()
      .remove();

}//update

/////////////////////////////////////////////////////////////
  ////////////////////// Brush functions //////////////////////
  /////////////////////////////////////////////////////////////

//First function that runs on a brush move
  function brushmove() {

var extent = brush.extent();

//Which bars are still "selected"
    var selected = mini_yScale.domain()
      .filter(function(d) { return (extent[0] - mini_yScale.rangeBand() + 1e-2 <= mini_yScale(d)) && (mini_yScale(d) <= extent[1] - 1e-2); }); 
    //Update the colors of the mini chart - Make everything outside the brush grey
    d3.select(".miniGroup").selectAll(".bar")
      .style("fill", function(d, i) { return selected.indexOf(d.country) > -1 ? "url(#gradient-rainbow-mini)" : "#e0e0e0"; });

//Update the label size
    d3.selectAll(".y.axis text")
      .style("font-size", textScale(selected.length));
    
    /////////////////////////////////////////////////////////////
    ///////////////////// Update the axes ///////////////////////
    /////////////////////////////////////////////////////////////

//Reset the part that is visible on the big chart
    var originalRange = main_yZoom.range();
    main_yZoom.domain( extent );

//Update the domain of the x & y scale of the big bar chart
    main_yScale.domain(data.map(function(d) { return d.country; }));
    main_yScale.rangeBands( [ main_yZoom(originalRange[0]), main_yZoom(originalRange[1]) ], 0.4, 0);

//Update the y axis of the big chart
    d3.select(".mainGroup")
      .select(".y.axis")
      .call(main_yAxis);

//Find the new max of the bars to update the x scale
    var newMaxXScale = d3.max(data, function(d) { return selected.indexOf(d.country) > -1 ? d.value : 0; });
    main_xScale.domain([0, newMaxXScale]);

//Update the x axis of the big chart
    d3.select(".mainGroupWrapper")
      .select(".x.axis")
      .transition().duration(50)
      .call(main_xAxis);

//Update the big bar chart
    update();
    
  }//brushmove

/////////////////////////////////////////////////////////////
  ////////////////////// Click functions //////////////////////
  /////////////////////////////////////////////////////////////

//Based on https://bl.ocks.org/mbostock/6498000
  //What to do when the user clicks on another location along the brushable bar chart
  function brushcenter() {
    var target = d3.event.target,
        extent = brush.extent(),
        size = extent[1] - extent[0],
        range = mini_yScale.range(),
        y0 = d3.min(range) + size / 2,
        y1 = d3.max(range) + mini_yScale.rangeBand() - size / 2,
        center = Math.max( y0, Math.min( y1, d3.mouse(target)[1] ) );

d3.event.stopPropagation();

gBrush
        .call(brush.extent([center - size / 2, center + size / 2]))
        .call(brush.event);

}//brushcenter

/////////////////////////////////////////////////////////////
  ///////////////////// Scroll functions //////////////////////
  /////////////////////////////////////////////////////////////

function scroll() {

//Mouse scroll on the mini chart
    var extent = brush.extent(),
      size = extent[1] - extent[0],
      range = mini_yScale.range(),
      y0 = d3.min(range),
      y1 = d3.max(range) + mini_yScale.rangeBand(),
      dy = d3.event.deltaY,
      topSection;

if ( extent[0] - dy < y0 ) { topSection = y0; } 
    else if ( extent[1] - dy > y1 ) { topSection = y1 - size; } 
    else { topSection = extent[0] - dy; }

//Make sure the page doesn't scroll as well
    d3.event.stopPropagation();
    d3.event.preventDefault();

gBrush
        .call(brush.extent([ topSection, topSection + size ]))
        .call(brush.event);

}//scroll

/////////////////////////////////////////////////////////////
  ///////////////////// Helper functions //////////////////////
  /////////////////////////////////////////////////////////////

//Create a gradient 
  function createGradient(idName, endPerc) {

var coloursRainbow = ["#EFB605", "#E9A501", "#E48405", "#E34914", "#DE0D2B", "#CF003E", "#B90050", "#A30F65", "#8E297E", "#724097", "#4F54A8", "#296DA4", "#0C8B8C", "#0DA471", "#39B15E", "#7EB852"];

defs.append("linearGradient")
      .attr("id", idName)
      .attr("gradientUnits", "userSpaceOnUse")
      .attr("x1", "0%").attr("y1", "0%")
      .attr("x2", endPerc).attr("y2", "0%")
      .selectAll("stop") 
      .data(coloursRainbow)                  
      .enter().append("stop") 
      .attr("offset", function(d,i) { return i/(coloursRainbow.length-1); })   
      .attr("stop-color", function(d) { return d; });
  }//createGradient

//Function to generate random strings of 5 letters - for the demo only
  function makeWord() {
      var possible_UC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
      var text = possible_UC.charAt(Math.floor(Math.random() * possible_UC.length));
      
      var possible_LC = "abcdefghijklmnopqrstuvwxyz";

for( var i=0; i < 5; i++ )
          text += possible_LC.charAt(Math.floor(Math.random() * possible_LC.length));

return text;
  }//makeWord

</script>

</body>
</html>

https://d3js.org/d3.v3.min.js