Change bar chart into pie chart - d3.js

Question

initiaa Bar chart
I want to convert this bar chart into pie chart. I have tried plaing around with the transition function and appending code. But it doesnot seem to work.
edited pen
Here's the code for my pie chart
var width = 150;
var height = 150;
var radius = Math.min(width, height) / 2;
var donutWidth = 75;
var legendRectSize = 18;
var legendSpacing = 4;
var color = d3.scale.category20b();
var svg = d3.select('#chart')
.append('svg')
.attr('width', width)
.attr('height', height)
.append('g')
.attr('transform', 'translate(' + (width / 2) +
',' + (height / 2) + ')');
var arc = d3.svg.arc()
.innerRadius(radius - donutWidth)
.outerRadius(radius);
var pie = d3.layout.pie()
.value(function (d) {
return d.count;
})
.sort(null);
var tooltip = d3.select('#chart')
.append('div')
.attr('class', 'tooltip');
tooltip.append('div')
.attr('class', 'label');
tooltip.append('div')
.attr('class', 'count');
tooltip.append('div')
.attr('class', 'percent');
//d3.csv('weekdays.csv', function (error, dataset) {
dataset.forEach(function (d) {
d.count = +d.count;
d.enabled = true; // NEW
});
var path = svg.selectAll('path')
.data(pie(dataset))
.enter()
.append('path')
.attr('d', arc)
.attr('fill', function (d, i) {
return color(d.data.label);
}) // UPDATED (removed semicolon)
.each(function (d) {
this._current = d;
}); // NEW
path.on('mouseover', function (d) {
var total = d3.sum(dataset.map(function (d) {
return (d.enabled) ? d.count : 0; // UPDATED
}));
var percent = Math.round(1000 * d.data.count / total) / 10;
tooltip.select('.label').html(d.data.label);
tooltip.select('.count').html(d.data.count);
tooltip.select('.percent').html(percent + '%');
tooltip.style('display', 'block');
});
path.on('mouseout', function () {
tooltip.style('display', 'none');
});

Answer 1

The data linkage seemd to be the issue. Everytime the console said invalid values.
Here;s the working fiddle
var data = [10,20,30,40,60, 80, 20, 50];
// the D3 bits...
var color = d3.scale.category10();
var width = 180;
var height = 180;
var pie = d3.layout.pie().sort(null);
var arc = d3.svg.arc()
.outerRadius(width / 2 * 0.9)
.innerRadius(width / 2 * 0.5);
var svg = d3.select(element[0]).append('svg')
.attr({width: width, height: height})
.append('g')
.attr('transform', 'translate(' + width / 2 + ',' + height / 2 + ')');
// add the <path>s for each arc slice
svg.selectAll('path').data(pie(data)) // our data
.enter().append('path')
.style('stroke', 'white')
.attr('d', arc)
.attr('fill', function(d, i){ return color(i) });