D3 Examples - Film Flowers, Single Starter Code

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<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.13.1/lodash.js'></script>
  <link href='https://fonts.googleapis.com/css?family=Libre+Baskerville:400,700' rel='stylesheet' type='text/css'>
  
  <style>
    svg {
      width: 600px;
      height: 20000px;
    }
  </style>
</head>
​
<body>
  <svg></svg>
  
  <script>
    const width = 600;
    const height = 600;
    
    const petalPaths = [[
        'M0,0',
      'C50,40 50,70 20,100',
      'L0,85',
      'L-20,100',
      'C-50,70 -50,40 0,0'
    ],
        [
      'M0,0',
      'C50,50 50,100 0,100',
      'C-50,100 -50,50 0,0'
    ],
        [
      'M0,0',
      'C50,50 50,100 0,75',
      'C-50,100 -50,50 0,0'
    ],
        [
      'M0,0',
      'C50,15 50,85 0,100',
      'C-50,85 -50,15 0,0'
    ]];
    
    // instantiate scales and petal path lookup
    const sizeScale = d3.scaleLinear()
        .range([0.1, 1]);
    const numPetalsScale = d3.scaleQuantize()
        .range(_.range(5, 10));
    const pathLookup = {
      G: petalPaths[0],
      PG: petalPaths[1],
      'PG-13': petalPaths[2],
      R: petalPaths[3],
    };
    
    // grab svg
    const svg = d3.select(' svg');
    
    /*****************************************************
    ** get movie data
    ******************************************************/
    
    d3.json('movies.json', function(movies) {
      movies = _.map(movies, movie => {
        return {
          rating: ++movie.imdbRating,
          votes: parseInt(movie.imdbVotes.replace(/\,/g, '')),
          year: ++movie.Year,
          title: movie.Title,
          pg: movie.Rated,
        }
      });
      
      // 1. set domain for scales
      const ratingExtent = d3.extent(movies, m => m.rating);
      const votesExtent = d3.extent(movies, m => m.votes);
      sizeScale.domain(ratingExtent);
      numPetalsScale.domain(votesExtent);
      
      // 2. create petal data for just the first movie
      const petalCount = numPetalsScale(movies[0].votes);
      const movieData = _.times(petalCount, (i) => {
        return {
          petalAngle: (i / petalCount) * 360,
          petalSize: sizeScale(movies[0].rating),
          petalType: pathLookup[movies[0].pg]
        };
      });
      
      // 3. draw the petals using d3's data-binding and enter-append
      svg.selectAll('.petal')
        .data(movieData).enter().append('path')
        .classed('petal', true)
        .attr('transform', d => {
          return `translate(100, 100)rotate(${d.petalAngle})scale(${d.petalSize})`;
        })
        .attr('d', d => d.petalType)
        .attr('fill', 'none')
        .attr('stroke', 'black')
        .attr('stroke-width', 1)
    });
    
  </script>
</body>
​
    