scenic_plot.js

/**
 * Min-max feature scaling: scale a percentage to be between 0-100
 * and return according hex colour, rendering from red to yellow to green.
 *
 * @param  {Number} perc Percentage to scale
 * @param  {Number} min  Minimum perc value
 * @param  {Number} max  Maximum perc value
 * @return {String}      Scaled hex colour
 **/
function percToColour(perc, min, max) {
  if (arguments.length < 3) throw "Insufficient number of parameters passed.";

  var a = 0,
    b = 100;
  perc = a + ((perc - min) * (b - a)) / (max - min);

  var r,
    g,
    b = 0;
  if (perc < 50) {
    r = 255;
    g = Math.round(5.1 * perc);
  } else {
    g = 255;
    r = Math.round(510 - 5.1 * perc);
  }
  var h = r * 0x10000 + g * 0x100 + b * 0x1;
  return "#" + ("000000" + h.toString(16)).slice(-6);
}

function reformat(array) {
  var data = [];
  array.map(function (d, i) {
    data.push({
      id: i,
      type: "Feature",
      properties: {
        scenic_rating: d.mean_rating_per_locid
      },
      geometry: {
        coordinates: [+d.lon, +d.lat],
        type: "Point"
      }
    });
  });
  return data;
}

/**
 * Scale a given mean scenic rating (for an LSOA) to be between 0 and 10,
 * according to the max and min in the dataset (2.16 and 4.84, respectively).
 *
 * @param  {Number} s_rate Scenic rating to scale
 * @return {Number}        Scaled scenic rating
 **/
function getScenicBar(s_rate) {
  var a = 0,
    b = 10;
  return a + ((s_rate - 2.16) * (b - a)) / (4.84 - 2.16);
}

/**
 * Scale a given income rate to be between 0, and 10, according
 * to the max and min in the dataset (.5 and 0, respectively).
 *
 * @param  {Number} inc_rate Income rate to scale
 * @return {Number}          Scaled income rate
 **/
function getIncomeBar(inc_rate) {
  var a = 0,
    b = 10;
  return b - (a + ((inc_rate - 0) * (b - a)) / (0.5 - 0));
}

/**
 * Scale a given health score to be between 0, and 10, according
 * to the max and min in the dataset (1.8 and -3.2, respectively).
 *
 * @param  {Number} h_score Health to scale
 * @return {Number}         Scaled health score
 **/
function getHealthBar(h_score) {
  var a = 0,
    b = 10;
  return b - (a + ((h_score + 3.2 - 0) * (b - a)) / (1.8 + 3.2 - 0));
}

/**
 * Scale a given employment score to be between 0, and 10, according
 * to the max and min in the dataset (.4 and 0, respectively).
 *
 * @param  {Number} e_score Employment score to scale
 * @return {Number}         Scaled employment score
 **/
function getEmploymentBar(e_score) {
  var a = 0,
    b = 10;
  return b - (a + ((e_score - 0) * (b - a)) / (0.4 - 0));
}

/**
 * Scale a given education score to be between 0, and 10, according
 * to the max and min in the dataset (64 and 0, respectively).
 *
 * @param  {Number} e_score Education score to scale
 * @return {Number}         Scaled education score
 **/
function getEducationBar(e_score) {
  var a = 0,
    b = 10;
  return b - (a + ((e_score - 0) * (b - a)) / (64 - 0));
}

/**
 * Scale a given education score to be between 0, and 10, according
 * to the max and min in the dataset (93.4 and 4, respectively).
 *
 * @param  {Number} e_score Living environment score to scale
 * @return {Number}         Scaled living environment score
 **/
function getLivingEnvBar(e_score) {
  var a = 0,
    b = 10;
  return b - (a + ((e_score - 4) * (b - a)) / (93.4 - 4));
}

/**
 * Get the appropariate colour of given number of crimes according
 * to prespecified bins (red- high counts, blue - low counts).
 *
 * @param  {Number} crime_count              Mean num of monthly crime counts
 * @param  {Bool}   [return_integer = false] Optional param to return integer category for crime count
 * @return {String}                          Hex colour for category of counts
 **/
function getCrimeColour(crime_count, return_integer) {
  if (return_integer) {
    return crime_count >= 50
      ? 10
      : crime_count >= 20
      ? 7.5
      : crime_count >= 10
      ? 5
      : crime_count >= 5
      ? 2.5
      : 0;
  }
  return crime_count >= 50
    ? "#a42e3d"
    : crime_count >= 20
    ? "#cb7572"
    : crime_count >= 10
    ? "#7fa4b4"
    : crime_count >= 5
    ? "#0e4b8d"
    : "#012043";
}