6.11 histogram | small multiple

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<html>
<head>

<link href="https://fonts.googleapis.com/css2?family=Montserrat+Alternates:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&family=Montserrat:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&family=Roboto:ital,wght@0,100;0,300;1,100;1,300&display=swap" rel="stylesheet">

<script src="https://d3js.org/d3.v4.min.js"></script>

<p id="h1">SMALL MULTIPLE  | HISTOGRAM </p> 
<div id="link">by
<a href="https://slides.com/sandravizmad">SANDRA</a></div>

<style>

/*Defining text stylings*/ 
  
#h1 {
  font-size:30px;
  margin:30px 0px 0px 20px;
  color:#f5fa91; 
  font-family:'Montserrat Alternates', sans-serif;
  font-weight:300;
}
   
#link {
	font-family:'Montserrat Alternates', sans-serif;
  font-weight:200;
  font-size:10px;
	margin:5px 0px 0px 22px;
  color:white;
}
 
a:link, a:visited, a:active {
	text-decoration: none;
  color:white;
  border-bottom:1.5px dotted white;
}
  
body {
  background-color:#011227;
}

/*Defining axis stylings*/

.y-axis text, .x-axis text {
  font-family:'Montserrat Alternates', sans-serif;
  font-weight:400;
  font-size:8px;
  opacity:1;
  fill:white;
}

.y-axis path {
  fill:none;
  stroke-width:0;
  stroke-opacity:1;
  stroke:white;
}
  
.x-axis path {
  fill:none;
  stroke-width:0;
  stroke-opacity:1;
  stroke:white;
}

.y-axis line, .x-axis line {
  fill:none;
  stroke-width:0.1;
  stroke-opacity:0.5;
  stroke:white;
  stroke-dasharray:2;
}
   
/*Defining chart stylings*/
  
#region {
   fill:black;
   font-family:'Montserrat Alternates', sans-serif;
   font-family:'Poiret One', cursive;
   font-size:12px; 
}
      
.bar {
  fill:#8ff798;
}
  
#label {
   fill:#f5fa91; 
   font-family:'Montserrat Alternates', sans-serif;
   font-size:11px; 
}
            	 		
</style>
</head>
  
<body>
<script>

//Margin conventions
var m = {top:0, right:0, bottom:0, left:0}
    w = 0 - m.left - m.right,
    h = 0 - m.top - m.bottom;

//Container
var svg = d3.select("body")
    .append("svg")
    .attr("width", w + m.left + m.right)
    .attr("height", h + m.top + m.bottom)
    .append("g")
    .attr("transform", `translate(${m.left}, ${m.top})`);
  
//Margin conventions for the small multiple container
var m_s = {top:20, right:50, bottom:50, left:30}
    w_s = 400 - m_s.left - m_s.right,
    h_s = 400 - m_s.top - m_s.bottom;

//Define the format
var parseDate = d3.timeParse("%d/%m/%Y");
var formatDate = d3.timeFormat("%Y");

//Data loading
d3.csv(
  "https://gist.githubusercontent.com/sandravizz/221448a76bf10751d522a3a892825eb0/raw/fe62c91476647525aeca0cbac86475b1bc629d93/data",
  prepare, 
  data => {

//X scale
var x = d3.scaleTime()
    .domain(d3.extent(data, d => d.date))
    .range([0, w_s])        
    .clamp(false);
    
//Nesting data by region  
var nest = d3.nest()
    .key(d => d.region)
    .entries(data);

//Histogram generator
var histo = d3.histogram()
    .value(d => d.date)
    .domain(x.domain())
    .thresholds(x.ticks(d3.timeYear));

//Applying the histogram generator to the data
var regions = nest.map(d => {return {
    key: d.key,
    values: histo(d.values)
}});

//Calculating the max by region
var localMax = regions.map(d => {return {
    region: d.key, 
    max: d3.max(d.values, s => s.length)
}})
  
//Find the global max as the domain for the y scale 
//Y scale
var y = d3.scaleLinear()
    .domain([0, d3.max(localMax, d => d.max)])
    .range([h_s, 40]);
      
 //Small multiple container
  var svg_s = d3.select("body")
  		.selectAll("svg")
      .data(regions)
      .enter()
  		.append("svg")
      .attr("width",  w_s + m_s.left + m_s.right)
      .attr("height", h_s + m_s.top + m_s.bottom)
      .append("g")
  		.attr("transform",`translate(${m_s.left}, ${m_s.top})`);

//For each region add a label 
svg_s.append("text")
     .attr("id", "region")
     .attr("x", m_s.left)
     .attr("y", m_s.top)
     .text(d => d.key)

//Draw histogram
var hist = svg_s.append("g")
    .attr("class","hist")
    .attr("transform",`translate(${m_s.left}, ${m_s.top})`);

//X axis
hist.append("g")
    .attr("class", "x-axis")
    .attr("transform", `translate(0, ${h_s})`)
    .call(d3.axisBottom(x)
            .tickValues(x.domain())
            .tickPadding(5)
            .tickFormat(formatDate));

//Data binding
var bar = hist.selectAll(".bar")
    .data(d => d.values)
    .enter()
    .append("g")
    .attr("class","bar")
    .attr("transform",s =>`translate(${x(s.x0)}, ${y(s.length)})`); 
  
//Adding labels to the bars
bar.append("text")
    .attr("id", "label")
    .attr("dy", ".75em")
    .attr("y", -12)
    .attr("x",s =>(x(s.x1) - x(s.x0))-15)
    .text(s => {if(s.length > 1) {return s.length;}});

//Draw the bars
bar.append("rect")
    .attr("class"," bar")
    .attr("x", 1)
    .attr("width", s => x(s.x1) - x(s.x0))
    .attr("height", s => h_s - y(s.length));
     
});

//Data format
function prepare(d) {
  d.date = parseDate(d.date);
return d;
}

</script>
</body>
</html>

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