D3 Block-a-Day: Day 8, January 8th, 2017

D3 Block-a-Day: Day 8, January, 8th 2017

New Year's Resolution for 2017: Make a D3 Block a day to teach myself D3. This is Number 8. This example builds on yesterday's Wyoming school district map adding tooltips that identify the district. The topoJSON files used to construct this visualization were created by me using shape files provided by the United States Census Bureau. The Center for Assessment makes these state and national school district topoJSON files available for anyone to use in their own development.

<!DOCTYPE html>
<meta charset="utf-8">
<head>
<title>D3 Block-a-Day: Day 8, January 8, 2017</title>
<style>

#wrapper {
      width: 100vw;
      height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
}
      
path {
  fill: #ccc;
  stroke: #fff;
  stroke-width: .5px;
}

path:hover {
  fill: #879baa;
}

.hidden {
  display: none;
}

div.tooltip {
  background-color: #fff8dc;
  padding: 7px;
  text-shadow: #f5f5f5 0 1px 0;
  font: 13px Helvetica Neue;
  border: 2.5px solid;
  border-color: black;
	border-radius: 3px;
  opacity: 0.9;
  position: absolute;
  box-shadow: rgba(0, 0, 0, 0.3) 0 2px 10px;
  }
</style>
</head>
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/topojson.v2.min.js"></script>
<script src="https://d3js.org/d3-array.v1.min.js"></script>
<script src="https://d3js.org/d3-geo.v1.min.js"></script>

var width = 960,
    height = 500;
  
  const zoom = d3.zoom()
      .scaleExtent([1/4, 3])
      .on('zoom', function () {
        d3.select('g').attr('transform', d3.event.transform)
      });

const svg = d3.select('#chart')
      .append('svg')
      .attr('width', width)
      .attr('height', height)
      .call(zoom)

const g = svg.append('g')
    
  var projection = d3.geoMercator()
			.center([ -107.5534, 43.00029 ])
			.scale(5000);

var path = d3.geoPath()
      .projection(projection);
  
  var tooltip = d3.select('#chart').append('div')
      .attr('class', 'hidden tooltip');

d3.json("WY_Districts.json", function(error, state_districts) {
  	if (error) throw error;

g.selectAll("path")
    	  .data(topojson.feature(state_districts, state_districts.objects.districts).features)
		    .enter()
		    .append("path")
    	  .attr("d", path)
        .on('mousemove', function(d) {
           var mouse = d3.mouse(svg.node()).map(function(d) {
                return parseInt(d);
         });
         tooltip.classed('hidden', false)
                .attr('style', 'left:' + (mouse[0] + 15) +'px; top:' + (mouse[1] - 35) + 'px')
                .html(d.properties.District);
         })
         .on('mouseout', function() {
                tooltip.classed('hidden', true);
         });;
	});
</script>
</body>

https://d3js.org/d3.v4.min.js

https://d3js.org/topojson.v2.min.js

https://d3js.org/d3-array.v1.min.js

https://d3js.org/d3-geo.v1.min.js