D3 Examples - Breakdown: Students on free and reduced lunch in Iowa

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    <head>
        <meta charset="utf-8">
        <title>Free and reduced lunch in Iowa</title>
        <script type="text/javascript" src="https://d3js.org/d3.v3.js"></script>
    </head>
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    <link rel="stylesheet" type="text/css" href="styles.css">
    <body>
        <h3>Breakdown: Students on free and reduced lunch in Iowa</h3>
        <p>This graph shows all the schools in Iowa where 50% or more of their students are on a free or reduced lunch program. A total of 64 school districts are shown.</p>
        <p>The y scale from top to bottom shows the percentage of students that each school has on one of those programs. The x scale from left to right shows the number of students on one of those programs.</p>
        <p>As the graph shows, most of the schools shown have less than 5,000 students.</p>
        <svg></svg>
        <p>To download the data, <a href="https://docs.google.com/spreadsheets/d/1KvLX4M8ww2js4GMWOX4niM9fApu0efvc59pLKAyeM-s/" target="_blank">click here</a>.</p>
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        <script type="text/javascript">     
            var width = 750;
            var height = 500;
            var padding = [40, 15, 35, 50];
​
            // Determines x scale
            // Based on data values
            var xScale = d3.scale.linear()
                // This is what is outputted
                .range([ padding[3] + 15, width - padding[3] ]);
​
            // Determines y scale
            // Based on number of values total
            var yScale = d3.scale.linear()
                // This is what is outputted
                .range([ padding[0] + 15, height - padding[2] ]);
​
            var xAxis = d3.svg.axis()
                .scale(xScale)
                .orient("top");
​
            var yAxis = d3.svg.axis()
                .scale(yScale)
                .orient("left")
                .tickFormat(function(d) {
                    return d + "%";
                });
​
            // Create empty SVG so we can append data to it later
            var svg = d3.select("svg")
                .attr("width", width)
                .attr("height", height);
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            // Load CSV data
            d3.csv("ia_free_reduced_50_higher.csv", function(data) {
                // Map school name to school value
                xScale.domain([ 
                    d3.min(data, function(d) {
                        return +d['FreeorReduced'];
                    }),
                    d3.max(data, function(d) {
                        return +d['FreeorReduced'];
                    })
                ]);
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                // Set second domain to max value in data
                yScale.domain([ 
                    d3.max(data, function(d) {
                        return +d['Percent'];
                    }),
                    d3.min(data, function(d) {
                        return +d['Percent'];
                    })
                ]);
​
                // Create circleangles and append to DOM
                var circles = svg.selectAll("circle")
                    .data(data)
                    .enter()
                    .append("circle");
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                // Set attributes
                circles.attr("cx", function(d, num) {
                        return xScale( d['FreeorReduced'] );
                    })
                    .attr("cy", function(d, num) {
                        return yScale( d['Percent'] );
                    })
                    .attr("r", 4)
                    .append("title")
                    
                    // Tooltip
                    .text(function(d) {
                        return 'The percentage of students on free or reduced lunch at ' + d['Name'] + ' High School is ' + d['Percent'] + '%. A total of ' + d['FreeorReduced'] + ' students are on the program.';
                    });
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                // Append x and y axis
                svg.append("g")
                    .attr("class", "x-axis axis")
                    .attr("transform", "translate(0," + padding[0] + ")")
                    .call(xAxis);
​
                svg.append("g")
                    .attr("class", "y-axis axis")
                    .attr("transform", "translate(" + padding[3] + ",0)")
                    .call(yAxis);
            });
        </script>
    </body>
</html>
    