paulgb/index.html

## index.html
<!DOCTYPE html>
<!-- By Jan Wrobel (http://mixedbit.org) -->

<html>

  <head>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8">
    <title>Random walk</title>
    <script type="text/javascript" src="http://d3js.org/d3.v3.min.js"></script>
    <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
    <script src="https://raw.github.com/mbostock/d3/master/lib/colorbrewer/colorbrewer.js"></script>
    <style type="text/css">

body {
  background: #222;
}

</style>
</head>
<body>
  <button type="button" onclick="faster();">Faster!</button>
<script type="text/javascript">

function init_array(size, init_v) {
  var result = [];
  for (i = 0; i < size; i += 1) {
    result.push(init_v);
  }
  return result;
}

var GRID = 5,
WALK_H = 280,
WALK_W = 2 * WALK_H,
PLOT_H = WALK_H / 2,
POINT_R = 4,
delay = 100,
result_cnt = init_array(WALK_W / GRID, 0),
svg = d3.select("body").append("svg:svg")
  .attr("width", WALK_W)
  .attr("height", WALK_H + PLOT_H + POINT_R),
PALETE = colorbrewer.Oranges[9].reverse();

$('button').attr('disabled', false);
walk(WALK_W / 2, 0);

function faster() {
  if (delay > 20) {
    delay -= 20;
  } else {
    delay = 0;
    $('button').attr('disabled', true);
  }
}
function append_result(final_x) {
  var result_idx = final_x / GRID;
  svg.append("svg:circle")
    .attr("cx", final_x)
    .attr("cy", WALK_H + POINT_R)
    .attr("r", POINT_R)
    .style("fill", "aliceblue")
    .style("opacity", 0.85)
    .transition()
    // Move the result point to the bottom of the plot.
    .attr("cy", WALK_H + PLOT_H - 2 * POINT_R * result_cnt[result_idx] )
    .duration(3000);
  result_cnt[result_idx] += 1;
}

function walk(x, y) {
  var x_end, y_end = y + GRID;
  if (Math.random() < 0.5) {
    x_end = x + GRID;
  } else {
    x_end = x - GRID;
  }
  line = svg.select('line[x1="' + x + '"][x2="' + x_end + '"]'+
                    '[y1="' + y + '"][y2="' + y_end + '"]');
  if (line.empty()) {
    // Create a new line segment
    svg.append("svg:line")
      .attr("x1", x)
      .attr("y1", y)
      .attr("x2", x_end)
      .attr("y2", y_end)
      .style("stroke", PALETE[0])
      .style("stroke-width", 2)
      .data([0]);
  } else {
    // or alter color of an existing line.
    var color_idx = Math.min(line.data() + 1, PALETE.length - 1);
    line.style('stroke', PALETE[color_idx])
      .datum(color_idx)
  }

  if (y_end >= WALK_H) {
    // End reached.
    append_result(x_end);
    x_end = WALK_W / 2;
    y_end = 0;
  }
  window.setTimeout(function() {
    walk(x_end, y_end);
  }, delay);
}

</script>
</body>
</html>
	<!DOCTYPE html>
	<!-- By Jan Wrobel (http://mixedbit.org) -->

	<html>

	<head>
	<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
	<title>Random walk</title>
	<script type="text/javascript" src="http://d3js.org/d3.v3.min.js"></script>
	<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
	<script src="https://raw.github.com/mbostock/d3/master/lib/colorbrewer/colorbrewer.js"></script>
	<style type="text/css">

	body {
	background: #222;
	}

	</style>
	</head>
	<body>
	<button type="button" onclick="faster();">Faster!</button>
	<script type="text/javascript">

	function init_array(size, init_v) {
	var result = [];
	for (i = 0; i < size; i += 1) {
	result.push(init_v);
	}
	return result;
	}

	var GRID = 5,
	WALK_H = 280,
	WALK_W = 2 * WALK_H,
	PLOT_H = WALK_H / 2,
	POINT_R = 4,
	delay = 100,
	result_cnt = init_array(WALK_W / GRID, 0),
	svg = d3.select("body").append("svg:svg")
	.attr("width", WALK_W)
	.attr("height", WALK_H + PLOT_H + POINT_R),
	PALETE = colorbrewer.Oranges[9].reverse();

	$('button').attr('disabled', false);
	walk(WALK_W / 2, 0);

	function faster() {
	if (delay > 20) {
	delay -= 20;
	} else {
	delay = 0;
	$('button').attr('disabled', true);
	}
	}
	function append_result(final_x) {
	var result_idx = final_x / GRID;
	svg.append("svg:circle")
	.attr("cx", final_x)
	.attr("cy", WALK_H + POINT_R)
	.attr("r", POINT_R)
	.style("fill", "aliceblue")
	.style("opacity", 0.85)
	.transition()
	// Move the result point to the bottom of the plot.
	.attr("cy", WALK_H + PLOT_H - 2 * POINT_R * result_cnt[result_idx] )
	.duration(3000);
	result_cnt[result_idx] += 1;
	}

	function walk(x, y) {
	var x_end, y_end = y + GRID;
	if (Math.random() < 0.5) {
	x_end = x + GRID;
	} else {
	x_end = x - GRID;
	}
	line = svg.select('line[x1="' + x + '"][x2="' + x_end + '"]'+
	'[y1="' + y + '"][y2="' + y_end + '"]');
	if (line.empty()) {
	// Create a new line segment
	svg.append("svg:line")
	.attr("x1", x)
	.attr("y1", y)
	.attr("x2", x_end)
	.attr("y2", y_end)
	.style("stroke", PALETE[0])
	.style("stroke-width", 2)
	.data([0]);
	} else {
	// or alter color of an existing line.
	var color_idx = Math.min(line.data() + 1, PALETE.length - 1);
	line.style('stroke', PALETE[color_idx])
	.datum(color_idx)
	}

	if (y_end >= WALK_H) {
	// End reached.
	append_result(x_end);
	x_end = WALK_W / 2;
	y_end = 0;
	}
	window.setTimeout(function() {
	walk(x_end, y_end);
	}, delay);
	}

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