JavaScript , D3 bar graph error using CSV

This is the script/html i am not sure what the problem here is the error I keep arriving at is. I messed around with the y and heigh variables but i am unable to get to a solution. Changed the parameters, changed values but of no avail. Please assist.

These are the errors:

Error: Invalid value for attribute y="NaN"

Error: Invalid value for attribute height="NaN"

This is the code:

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.bar {
fill: steelblue;
}

.bar:hover {
fill: brown;
}
.axis {
font: 10px sans-serif;
}

.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}

.x.axis path {
display: none;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var margin = {top: 20, right: 20, bottom: 30, left: 40},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;

var x = d3.scale.ordinal()
.rangeRoundBands([0, width], .1);

var y = d3.scale.linear()
.range([height, 0]);

var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.ticks(1)

var yAxis = d3.svg.axis()
.scale(y)
.orient("left")
.ticks(1.0);

var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");

d3.csv("Unemployment.csv", type, function(error, data) {
if (error) throw error;

x.domain([0, d3.max(data, function(d) { return d.letter; })]);
y.domain([0, d3.max(data, function(d) { return d.frequency; })]);

svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);

svg.append("g")
.attr("class", "y axis")
.call(yAxis)
.append("text")

.attr("transform", "rotate(-90)")
.attr("y", 6)
.attr("dy", ".71em")
.style("text-anchor", "end")
.text("Frequency");

svg.selectAll(".bar")
.data(data)
.enter().append("rect")
.attr("class", "bar")
.attr("x", function(d) { return x(d.letter); })
.attr("width", x.rangeBand())
.attr("y", function(d) { return y(d.frequency); })
.attr("height", function(d) { return height - y(d.frequency); });
 });

function type(d) {
d.frequency = +d.frequency;
return d;
}

</script>


Ward,Unemployment
1,4.5
2,4.3
3,4.0
4,5.7
5,7.9
6,5.2
7,11.0
8,14.2

Answers


Problem 1

You doing

function type(d) {
d.frequency = +d.frequency;
return d;
}

It should have been (convert d.Unemployment from string to number):

function type(d) {
   d.Unemployment = +d.Unemployment;
  return d;
}

Problem 2

x.domain is a ordinal scale so it will not have a max min:

  //this is wrong
  x.domain([0, d3.max(data, function(d) { return d.letter; })]);
  //This is right
  x.domain(data.map(function(d) { return d.Ward; }));

Problem 3

y.domain is wrong

You are doing (there is no variable frequency)

y.domain([0, d3.max(data, function(d) { return d.frequency; })]);

It should have been

  y.domain([0, d3.max(data, function(d) {
    return d.Unemployment;
  })]);

working code here


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