chunheisiu · March 25, 2017 01:52
diff --git a/.block b/.block
 license: mit
diff --git a/README.md b/README.md
diff --git a/chart.js b/chart.js
 var updateData = function() {
  // get the textarea "value" (i.e. the entered text)
  var text = d3.select("body").select("textarea").node().value;

  // make sure we got the right text
  // console.log(text);

  // get letter count
  var count = countLetters(text);

  // some browsers support console.table()
  try {
    console.table(count.entries());
  }
  catch (e) {
    console.log(count);
  }

  return count;
 };

 /*
 * our massive function to draw a bar chart. note some stuff in here
 * is bonus material (for transitions and updating the text)
 */
 var drawBarChart = function() {
  // get the data to visualize
  var count = updateData();

  // get the svg to draw on
  var svg = d3.select("body").select("svg");

  /*
   * we will need to map our data domain to our svg range, which
   * means we need to calculate the min and max of our data
   */

  var countMin = 0; // always include 0 in a bar chart!
  var countMax = d3.max(count.values());
  console.log("count bounds:", [countMin, countMax]);

  /*
   * before we draw, we should decide what kind of margins we
   * want. this will be the space around the core plot area,
   * where the tick marks and axis labels will be placed
   * http://bl.ocks.org/mbostock/3019563
   */
  var margin = {
    top:    15,
    right:  10, // leave space for y-axis
    bottom: 30, // leave space for x-axis
    left:   35
  };

  // now we can calculate how much space we have to plot
  var bounds = svg.node().getBoundingClientRect();
  var plotWidth = bounds.width - margin.right - margin.left;
  var plotHeight = bounds.height - margin.top - margin.bottom;

  /*
   * okay now somehow we have to figure out how to map a count value
   * to a bar height, decide bar widths, and figure out how to space
   * bars for each letter along the x-axis
   *
   * this is where the scales in d3 come in very handy
   * https://github.com/d3/d3-scale#api-reference
   */

  /*
   * the counts are easiest because they are numbers and we can use
   * a simple linear scale, but the complicating matter is the
   * coordinate system in svgs:
   * https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Positions
   *
   * so we want to map our min count (0) to the max height of the plot area
   */
  var countScale = d3.scaleLinear()
    .domain([countMin, countMax])
    .range([plotHeight, 0])
    .nice(); // rounds the domain a bit for nicer output

  /*
   * the letters need an ordinal scale instead, which is used for
   * categorical data. we want a bar space for all letters, not just
   * the ones we found, and spaces between bars.
   * https://github.com/d3/d3-scale#band-scales
   */
  var letterScale = d3.scaleBand()
    .domain(letters)
    .rangeRound([0, plotWidth])
    .paddingInner(0.1); // space between bars

  // try using these scales in the console
  console.log("count scale [0, 36]:", [countScale(0), countScale(36)]);
  console.log("letter scale [a, z]:", [letterScale('a'), letterScale('z')]);

  // we are actually going to draw on the "plot area"
  var plot = svg.select("g#plot");

  if (plot.size() < 1) {
    // this is the first time we called this function
    // we need to steup the plot area
    plot = svg.append("g").attr("id", "plot");

    // notice in the "elements" view we now have a g element!

    // shift the plot area over by our margins to leave room
    // for the x- and y-axis
    plot.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
  }

  // now lets draw our x- and y-axis
  // these require our x (letter) and y (count) scales
  var xAxis = d3.axisBottom(letterScale);
  var yAxis = d3.axisLeft(countScale);

  // check if we have already drawn our axes
  if (plot.select("g#y-axis").size() < 1) {
    var xGroup = plot.append("g").attr("id", "x-axis");

    // the drawing is triggered by call()
    xGroup.call(xAxis);

    // notice it is at the top of our svg
    // we need to translate/shift it down to the bottom
    xGroup.attr("transform", "translate(0," + plotHeight + ")");

    // do the same for our y axix
    var yGroup = plot.append("g").attr("id", "y-axis");
    yGroup.call(yAxis);
    //yGroup.attr("transform", "translate(" + plotWidth + ",0)");
  }
  else {
    // we need to do this so our chart updates
    // as we type new letters in our box
    plot.select("g#y-axis").call(yAxis);
  }

  // now how about some bars!

  /*
   * time to bind each data element to a rectangle in our visualization
   * hence the name data-driven documents (d3)
   */
  var bars = plot.selectAll("rect")
    .data(count.entries(), function(d) { return d.key; });

  // setting the "key" is important... this is how d3 will tell
  // what is existing data, new data, or old data

  /*
   * okay, this is where things get weird. d3 uses an enter, update,
   * exit pattern for dealing with data. think of it as new data,
   * existing data, and old data. for the first time, everything is new!
   * http://bost.ocks.org/mike/join/
   */

  // we use the enter() selection to add new bars for new data
  bars.enter().append("rect")
    // we will style using css
    .attr("class", "bar")
    // the width of our bar is determined by our band scale
    .attr("width", letterScale.bandwidth())
    // we must now map our letter to an x pixel position
    .attr("x", function(d) {
      return letterScale(d.key);
    })
    // and do something similar for our y pixel position
    .attr("y", function(d) {
      return countScale(d.value);
    })
    // here it gets weird again, how do we set the bar height?
    .attr("height", function(d) {
      return plotHeight - countScale(d.value);
    });

  // notice there will not be bars created for missing letters!

  // so what happens when we change the text?
  // well our data changed, and there will be a new enter selection!
  // only new letters will get new bars

  // but we have to bind this draw function to textarea events
  // (see index.html)

  // for bars that already existed, we must use the update selection
  // and then update their height accordingly
  // we use transitions for this to avoid change blindness
  bars.transition()
    .attr("y", function(d) { return countScale(d.value); })
    .attr("height", function(d) { return plotHeight - countScale(d.value); });

  // what about letters that disappeared?
  // we use the exit selection for those to remove the bars
  bars.exit().transition()
    .attr("y", function(d) { return countScale(countMin); })
    .attr("height", function(d) { return plotHeight - countScale(countMin); })
    .remove();
 };
diff --git a/count.js b/count.js
 // this file includes code for the letter count

 // array of all lowercase letters
 var letters = "abcdefghijklmnopqrstuvwxyz".split("");

 /*
 * try this out in the console! you can access any variable or function
 * defined globally in the console
 *
 * and, you can right-click output in the console to make it global too!
 */

 /*
 * removes any character (including spaces) that is not a letter
 * and converts all remaining letters to lowercase
 */
 var onlyLetters = function(text) {
  // there are multiple ways to define a function in javascript!
  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions

  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp
  var notLetter = /[^a-z]/g;
  return text.toLowerCase().replace(notLetter, "");
 };

 // in console try: onlyLetters("hello world!");

 /*
 * counts all of the letters in the input text and stores the counts as
 * a d3 map object
 * https://github.com/d3/d3-collection/blob/master/README.md#map
 */
 var countLetters = function(input) {
  var text = onlyLetters(input);
  var count = d3.map();

  /*
   * you can loop through strings as if they are arrays
   * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for
   */
  for (var i = 0; i < text.length; i++) {
    var letter = text[i];

    // check if we have seen this letter before
    if (count.has(letter)) {
      count.set(letter, count.get(letter) + 1);
    }
    else {
      count.set(letter, 1);
    }
  }

  return count;
 };

 // in console try: countLetters("hello world!");
 // in console try: countLetters("hello world!").keys();
 // in console try: countLetters("hello world!").entries();
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <!-- we are using html 5 -->

 <head>
 <meta charset="utf-8">

 <title>Letter Count Bar Chart</title>

 <!-- this allows us to use the non-standard Roboto web font -->
 <link href="https://fonts.googleapis.com/css?family=Roboto:300,300italic" rel="stylesheet" type="text/css">

 <!-- this is our custom css stylesheet -->
 <link href="style.css" rel="stylesheet" type="text/css">
 </head>

 <body>
 <!-- we will place our visualization in this svg using d3.js -->
 <svg></svg>

 <!-- we will place the text to analyze here using javascript -->
 <textarea></textarea>

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

 <!-- include custom javascript -->
 <script src="count.js"></script>
 <script src="chart.js"></script>

 <!-- here is our core javascript -->
 <script type="text/javascript">
 // inside the script tag, // and /* */ are comments
 // outside the script tag, <!-- --> are comments

 // we need to load the text file into the textarea
 // this will be done asynchronously!
 // https://github.com/d3/d3-request/blob/master/README.md#text
 d3.text("peter.txt", function(error, data) {
    // we are creating a function within a method call here

    if (error) throw error;

    // we will use the console and developer tools extensively
    console.log(data);

    // now we select the textarea from the DOM and update
    // https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model
    // https://github.com/d3/d3-selection/blob/master/README.md#select
    d3.select("body").select("textarea").text(data);

    // updateData();
    drawBarChart();
 });

 // this message will appear BEFORE the text is logged!
 console.log("after d3.text() call");

 // add an event listener to our text area and
 // update our chart every time new data is entered
 d3.select("body").select("textarea")
  .on("keyup", drawBarChart);
 </script>

 </body>
diff --git a/peter.txt b/peter.txt
 Charles Chun Hei Siu
 Peter Piper picked a peck of pickled peppers.
 A peck of pickled peppers Peter Piper picked.
 If Peter Piper picked a peck of pickled peppers,
 Where's the peck of pickled peppers that Peter Piper picked?
diff --git a/style.css b/style.css
 /*
 * we use css to style our page and our svg elements
 * the classes/ids defined here must match our d3 code
 */

 body, textarea {
  font-family: 'Roboto', sans-serif;
  font-weight: 300;
  font-size: 11pt;
 }

 body {
  margin: 5px;
  padding: 0px;

  /* see https://developer.mozilla.org/en-US/docs/Web/CSS/color_value */
  background-color: whitesmoke;
 }

 textarea {
  /* position the textarea on top of the svg */
  position: fixed;
  top: 5px;
  right: 5px;

  margin: 0px;
  padding: 5px;

  width: 400px;
  height: 75px;

  /* try changing this color in blockbuilder! */
  background-color: rgba(255, 255, 255, 0.8);
 }

 textarea, svg {
  border: 1px solid gainsboro;
  border-radius: 10px;
 }

 svg {
  /* bl.ocks.org defaults to 960px by 500px */
  width: 950px;
  height: 490px;

  background-color: white;
 }

 /* svg elements are styled differently from html elements */

 rect.bar {
  stroke: none;
  fill: blue;
 }

 #x-axis text,
 #y-axis text {
  font-size: 10pt;
  fill: #888888;
 }

 #x-axis line {
  /* tick marks */
  fill: none;
  stroke: none;
 }

 #x-axis path,
 #y-axis path,
 #y-axis line {
  fill: none;

  stroke: #bbbbbb;
  stroke-width: 1px;
 }
	var updateData = function() {
	// get the textarea "value" (i.e. the entered text)
	var text = d3.select("body").select("textarea").node().value;

	// make sure we got the right text
	// console.log(text);

	// get letter count
	var count = countLetters(text);

	// some browsers support console.table()
	try {
	console.table(count.entries());
	}
	catch (e) {
	console.log(count);
	}

	return count;
	};

	/*
	* our massive function to draw a bar chart. note some stuff in here
	* is bonus material (for transitions and updating the text)
	*/
	var drawBarChart = function() {
	// get the data to visualize
	var count = updateData();

	// get the svg to draw on
	var svg = d3.select("body").select("svg");

	/*
	* we will need to map our data domain to our svg range, which
	* means we need to calculate the min and max of our data
	*/

	var countMin = 0; // always include 0 in a bar chart!
	var countMax = d3.max(count.values());
	console.log("count bounds:", [countMin, countMax]);

	/*
	* before we draw, we should decide what kind of margins we
	* want. this will be the space around the core plot area,
	* where the tick marks and axis labels will be placed
	* http://bl.ocks.org/mbostock/3019563
	*/
	var margin = {
	top: 15,
	right: 10, // leave space for y-axis
	bottom: 30, // leave space for x-axis
	left: 35
	};

	// now we can calculate how much space we have to plot
	var bounds = svg.node().getBoundingClientRect();
	var plotWidth = bounds.width - margin.right - margin.left;
	var plotHeight = bounds.height - margin.top - margin.bottom;

	/*
	* okay now somehow we have to figure out how to map a count value
	* to a bar height, decide bar widths, and figure out how to space
	* bars for each letter along the x-axis
	*
	* this is where the scales in d3 come in very handy
	* https://github.com/d3/d3-scale#api-reference
	*/

	/*
	* the counts are easiest because they are numbers and we can use
	* a simple linear scale, but the complicating matter is the
	* coordinate system in svgs:
	* https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Positions
	*
	* so we want to map our min count (0) to the max height of the plot area
	*/
	var countScale = d3.scaleLinear()
	.domain([countMin, countMax])
	.range([plotHeight, 0])
	.nice(); // rounds the domain a bit for nicer output

	/*
	* the letters need an ordinal scale instead, which is used for
	* categorical data. we want a bar space for all letters, not just
	* the ones we found, and spaces between bars.
	* https://github.com/d3/d3-scale#band-scales
	*/
	var letterScale = d3.scaleBand()
	.domain(letters)
	.rangeRound([0, plotWidth])
	.paddingInner(0.1); // space between bars

	// try using these scales in the console
	console.log("count scale [0, 36]:", [countScale(0), countScale(36)]);
	console.log("letter scale [a, z]:", [letterScale('a'), letterScale('z')]);

	// we are actually going to draw on the "plot area"
	var plot = svg.select("g#plot");

	if (plot.size() < 1) {
	// this is the first time we called this function
	// we need to steup the plot area
	plot = svg.append("g").attr("id", "plot");

	// notice in the "elements" view we now have a g element!

	// shift the plot area over by our margins to leave room
	// for the x- and y-axis
	plot.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
	}

	// now lets draw our x- and y-axis
	// these require our x (letter) and y (count) scales
	var xAxis = d3.axisBottom(letterScale);
	var yAxis = d3.axisLeft(countScale);

	// check if we have already drawn our axes
	if (plot.select("g#y-axis").size() < 1) {
	var xGroup = plot.append("g").attr("id", "x-axis");

	// the drawing is triggered by call()
	xGroup.call(xAxis);

	// notice it is at the top of our svg
	// we need to translate/shift it down to the bottom
	xGroup.attr("transform", "translate(0," + plotHeight + ")");

	// do the same for our y axix
	var yGroup = plot.append("g").attr("id", "y-axis");
	yGroup.call(yAxis);
	//yGroup.attr("transform", "translate(" + plotWidth + ",0)");
	}
	else {
	// we need to do this so our chart updates
	// as we type new letters in our box
	plot.select("g#y-axis").call(yAxis);
	}

	// now how about some bars!

	/*
	* time to bind each data element to a rectangle in our visualization
	* hence the name data-driven documents (d3)
	*/
	var bars = plot.selectAll("rect")
	.data(count.entries(), function(d) { return d.key; });

	// setting the "key" is important... this is how d3 will tell
	// what is existing data, new data, or old data

	/*
	* okay, this is where things get weird. d3 uses an enter, update,
	* exit pattern for dealing with data. think of it as new data,
	* existing data, and old data. for the first time, everything is new!
	* http://bost.ocks.org/mike/join/
	*/

	// we use the enter() selection to add new bars for new data
	bars.enter().append("rect")
	// we will style using css
	.attr("class", "bar")
	// the width of our bar is determined by our band scale
	.attr("width", letterScale.bandwidth())
	// we must now map our letter to an x pixel position
	.attr("x", function(d) {
	return letterScale(d.key);
	})
	// and do something similar for our y pixel position
	.attr("y", function(d) {
	return countScale(d.value);
	})
	// here it gets weird again, how do we set the bar height?
	.attr("height", function(d) {
	return plotHeight - countScale(d.value);
	});

	// notice there will not be bars created for missing letters!

	// so what happens when we change the text?
	// well our data changed, and there will be a new enter selection!
	// only new letters will get new bars

	// but we have to bind this draw function to textarea events
	// (see index.html)

	// for bars that already existed, we must use the update selection
	// and then update their height accordingly
	// we use transitions for this to avoid change blindness
	bars.transition()
	.attr("y", function(d) { return countScale(d.value); })
	.attr("height", function(d) { return plotHeight - countScale(d.value); });

	// what about letters that disappeared?
	// we use the exit selection for those to remove the bars
	bars.exit().transition()
	.attr("y", function(d) { return countScale(countMin); })
	.attr("height", function(d) { return plotHeight - countScale(countMin); })
	.remove();
	};
	// this file includes code for the letter count

	// array of all lowercase letters
	var letters = "abcdefghijklmnopqrstuvwxyz".split("");

	/*
	* try this out in the console! you can access any variable or function
	* defined globally in the console
	*
	* and, you can right-click output in the console to make it global too!
	*/

	/*
	* removes any character (including spaces) that is not a letter
	* and converts all remaining letters to lowercase
	*/
	var onlyLetters = function(text) {
	// there are multiple ways to define a function in javascript!
	// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions

	// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp
	var notLetter = /[^a-z]/g;
	return text.toLowerCase().replace(notLetter, "");
	};

	// in console try: onlyLetters("hello world!");

	/*
	* counts all of the letters in the input text and stores the counts as
	* a d3 map object
	* https://github.com/d3/d3-collection/blob/master/README.md#map
	*/
	var countLetters = function(input) {
	var text = onlyLetters(input);
	var count = d3.map();

	/*
	* you can loop through strings as if they are arrays
	* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for
	*/
	for (var i = 0; i < text.length; i++) {
	var letter = text[i];

	// check if we have seen this letter before
	if (count.has(letter)) {
	count.set(letter, count.get(letter) + 1);
	}
	else {
	count.set(letter, 1);
	}
	}

	return count;
	};

	// in console try: countLetters("hello world!");
	// in console try: countLetters("hello world!").keys();
	// in console try: countLetters("hello world!").entries();
	<!DOCTYPE html>
	<!-- we are using html 5 -->

	<head>
	<meta charset="utf-8">

	<title>Letter Count Bar Chart</title>

	<!-- this allows us to use the non-standard Roboto web font -->
	<link href="https://fonts.googleapis.com/css?family=Roboto:300,300italic" rel="stylesheet" type="text/css">

	<!-- this is our custom css stylesheet -->
	<link href="style.css" rel="stylesheet" type="text/css">
	</head>

	<body>
	<!-- we will place our visualization in this svg using d3.js -->
	<svg></svg>

	<!-- we will place the text to analyze here using javascript -->
	<textarea></textarea>

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

	<!-- include custom javascript -->
	<script src="count.js"></script>
	<script src="chart.js"></script>

	<!-- here is our core javascript -->
	<script type="text/javascript">
	// inside the script tag, // and /* */ are comments
	// outside the script tag, <!-- --> are comments

	// we need to load the text file into the textarea
	// this will be done asynchronously!
	// https://github.com/d3/d3-request/blob/master/README.md#text
	d3.text("peter.txt", function(error, data) {
	// we are creating a function within a method call here

	if (error) throw error;

	// we will use the console and developer tools extensively
	console.log(data);

	// now we select the textarea from the DOM and update
	// https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model
	// https://github.com/d3/d3-selection/blob/master/README.md#select
	d3.select("body").select("textarea").text(data);

	// updateData();
	drawBarChart();
	});

	// this message will appear BEFORE the text is logged!
	console.log("after d3.text() call");

	// add an event listener to our text area and
	// update our chart every time new data is entered
	d3.select("body").select("textarea")
	.on("keyup", drawBarChart);
	</script>

	</body>
	Charles Chun Hei Siu
	Peter Piper picked a peck of pickled peppers.
	A peck of pickled peppers Peter Piper picked.
	If Peter Piper picked a peck of pickled peppers,
	Where's the peck of pickled peppers that Peter Piper picked?
	/*
	* we use css to style our page and our svg elements
	* the classes/ids defined here must match our d3 code
	*/

	body, textarea {
	font-family: 'Roboto', sans-serif;
	font-weight: 300;
	font-size: 11pt;
	}

	body {
	margin: 5px;
	padding: 0px;

	/* see https://developer.mozilla.org/en-US/docs/Web/CSS/color_value */
	background-color: whitesmoke;
	}

	textarea {
	/* position the textarea on top of the svg */
	position: fixed;
	top: 5px;
	right: 5px;

	margin: 0px;
	padding: 5px;

	width: 400px;
	height: 75px;

	/* try changing this color in blockbuilder! */
	background-color: rgba(255, 255, 255, 0.8);
	}

	textarea, svg {
	border: 1px solid gainsboro;
	border-radius: 10px;
	}

	svg {
	/* bl.ocks.org defaults to 960px by 500px */
	width: 950px;
	height: 490px;

	background-color: white;
	}

	/* svg elements are styled differently from html elements */

	rect.bar {
	stroke: none;
	fill: blue;
	}

	#x-axis text,
	#y-axis text {
	font-size: 10pt;
	fill: #888888;
	}

	#x-axis line {
	/* tick marks */
	fill: none;
	stroke: none;
	}

	#x-axis path,
	#y-axis path,
	#y-axis line {
	fill: none;

	stroke: #bbbbbb;
	stroke-width: 1px;
	}