unable to load csv to d3 scatter plot - javascript

Below is my d3 code, it works perfectly if I mention the dataset with its numbers. However, when i want to take data from a csv file, it doesn't not accept it.
*ERROR
Error: Invalid value for <circle> attribute cx="NaN"
Here how the csv looks like:
t Or
16610 20635
14920 19532
13131 14814
15882 15745
15769 14993
15989 22557
14895 15387
17915 19758
Although if I try in google chrome,
console.log(dataset)
I get the data from csv but when i run it to apply, it just doesn't work in the browser.
I am using brackets as my IDE and google chrome as my default browser.
<body>
<h1> Hello World!! </h1>
<script type="text/javascript">
var dataset;
d3.csv("t.csv", function(d) {
dataset = d;
var h = 500;
var w = 1200;
var padding = 30;
var xscale = d3.scale.linear()
.domain([0,d3.max(dataset, function(d) { return d[0];})])
.range([padding, w- padding*2]);
var yscale = d3.scale.linear()
.domain([0, d3.max(dataset, function(d) { return d[1];})])
.range([h-padding,padding]);
var rscale = d3.scale.linear()
.domain([0,d3.max(dataset , function(d) { return d[1];})])
.range([5,30]);
var xAxis = d3.svg.axis()
.scale(xscale)
.orient("bottom");
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
var circle = svg.selectAll("circle")
.data(dataset)
.enter()
.append("circle")
.attr("cx", function(d) { return xscale(d[0]);})
.attr("cy", function(d) { return yscale(d[1]);})
.attr("r",function(d) { return rscale(d[1]);})
.on("mouseover", function(){d3.select(this).style("fill", "yellow");})
.on("mouseout", function(){d3.select(this).style("fill", function(dataset) { return "rgb(0,0," +(d*10) + ")";});});
var text = svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) { return d[0] + "," + d[1];})
.attr("x", function(d) { return xscale(d[0]);})
.attr("y", function(d) { return yscale(d[1]);})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill" ,"red");
svg.append("g")
.attr("class", "axis")
.attr("transform", "translate(0, " + (h - padding) +")")
.call(xAxis);
});
</script>
</body>

I just tweaked my above code. using the below which i found right here
It worked
var dataset;
d3.csv("t.csv", function(error, d) {
dataset = d.map(function(d) { return [ +d["t"], +d["Or"] ]; });

Related

Conditional Bar Chart with D3

I have a D3 visualization with a map and a bar chart. I am trying to get the bar chart to change depending on which circle on the map is clicked. Not sure how to do this. I have a function in my bar_chart.js file named update(newData) and a few extra arrays for the different circles on the map. Here is the link to the bl.ocks for the map and bar char.
js code for map
var myData = [21, 3, 5, 21, 15];
//Width and height
var w = 200;
var h = 125;
var yScale = null;
function draw(initialData) {
var xScale = d3.scale.ordinal()
.domain(d3.range(initialData.length))
.rangeRoundBands([0, w], 0.05);
yScale = d3.scale.linear()
.domain([0, d3.max(initialData)])
.range([0, h]);
//Create SVG element
var svg = d3.select("#chart")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
.data(initialData)
.enter()
.append("rect")
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d);
})
.attr("width", xScale.rangeBand())
.attr("height", function(d) {
return yScale(d);
})
.attr("fill", "steelblue");
svg.selectAll("text")
.data(initialData)
.enter()
.append("text")
.text(function(d) {
return d;
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return xScale(i) + xScale.rangeBand() / 2;
})
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
}
draw(myData);
//update function
function update(newData) {
yScale.domain([0, d3.max(newData)]);
var rects = d3.select("#chart svg")
.selectAll("rect")
.data(newData);
// enter selection
rects
.enter().append("rect");
// update selection
rects
.transition()
.duration(300)
.attr("y", function(d) {
return h - yScale(d);
})
.attr("height", function(d) {
return yScale(d);
})
// exit selection
rects
.exit().remove();
var texts = d3.select("#chart svg")
.selectAll("text")
.data(newData);
// enter selection
texts
.enter().append("rect");
// update selection
texts
.transition()
.duration(300)
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.text(function(d) {
return d;
})
// exit selection
texts
.exit().remove();
}
var mk = [10,17,20,14,8];
var cn = [18,4,9,20,15];
var nd = [5,12,7,15,21];
d3.select("#update").on("click", function() { update(newData); });
You have to incorporate the barchart data in your cities.csv file.
In the on-click handler of cities.csv where you show the tooltip you have to transform the data from the CSV into an array and call the bar chart update() method with this array.
One way of doing is to replace the , from the bar chart data with another char and split the string and convert the parts to numbers.
var cityData = d.barchart.split('#').map(Number);
update(cityData);
You also have to set the attributes of the new rects and texts of the bar chart. And the x-position will change if the number of bars change.

update d3 chart with new data

I want to update the bar chart with new data and I looked over this question:
How to update d3.js bar chart with new data
But it is not working for me. Probably because I don't know where to put the exit().remove() functions within my code. I tried putting this line
svg.selectAll("rect").exit().remove();
below the create bars section but it just removes all of the labels. Then, if I put it right after the create labels portion it removes the chart entirely. How can I get the update button change the chart with new data?
function draw(data) {
//Width and height
var w = 250;
var h = 250;
var xScale = d3.scale.ordinal()
.domain(d3.range(data.length))
.rangeRoundBands([0, w], 0.05);
var yScale = d3.scale.linear()
.domain([0, d3.max(data)])
.range([0, h]);
//Create SVG element
var svg = d3.select("#chart")
.append("svg")
.attr("width", w)
.attr("height", h);
//Create bars
svg.selectAll("rect")
.data(data)
.enter()
.append("rect")
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d);
})
.attr("width", xScale.rangeBand())
.attr("height", function(d) {
return yScale(d);
})
.attr("fill", "steelblue");
//Create labels
svg.selectAll("text")
.data(data)
.enter()
.append("text")
.text(function(d) {
return d;
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return xScale(i) + xScale.rangeBand() / 2;
})
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
};
function update() {
var data = [ 25, 22, 18, 15, 13 ];
draw(data);
}
var data = [ 21, 3, 5, 21, 15 ];
window.onload = draw(data);
With d3v3 (as I can see from your code you use this version) you should update your chart this way:
In update function set the new domain for yScale:
function update(newData) {
yScale.domain([0, d3.max(newData)]);
After that, apply new selection with selectAll("rect").data(newData), store selection in rects variable and set new value for appropriate attributes (if you do not want animation effect, remove .transition() .duration(300)):
var rects = d3.select("#chart svg")
.selectAll("rect")
.data(newData);
// enter selection
rects
.enter().append("rect");
// update selection
rects
.transition()
.duration(300)
.attr("y", function(d) {
return h - yScale(d);
})
.attr("height", function(d) {
return yScale(d);
})
Exit selection with exit method:
rects
.exit().remove();
Do the same way with text. I rewrite your code, look at the example in a hidden snippet below:
var myData = [21, 3, 5, 21, 15];
//Width and height
var w = 250;
var h = 250;
var yScale = null;
function draw(initialData) {
var xScale = d3.scale.ordinal()
.domain(d3.range(initialData.length))
.rangeRoundBands([0, w], 0.05);
yScale = d3.scale.linear()
.domain([0, d3.max(initialData)])
.range([0, h]);
//Create SVG element
var svg = d3.select("#chart")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
.data(initialData)
.enter()
.append("rect")
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d);
})
.attr("width", xScale.rangeBand())
.attr("height", function(d) {
return yScale(d);
})
.attr("fill", "steelblue");
svg.selectAll("text")
.data(initialData)
.enter()
.append("text")
.text(function(d) {
return d;
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return xScale(i) + xScale.rangeBand() / 2;
})
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
}
function update(newData) {
yScale.domain([0, d3.max(newData)]);
var rects = d3.select("#chart svg")
.selectAll("rect")
.data(newData);
// enter selection
rects
.enter().append("rect");
// update selection
rects
.transition()
.duration(300)
.attr("y", function(d) {
return h - yScale(d);
})
.attr("height", function(d) {
return yScale(d);
})
// exit selection
rects
.exit().remove();
var texts = d3.select("#chart svg")
.selectAll("text")
.data(newData);
// enter selection
texts
.enter().append("rect");
// update selection
texts
.transition()
.duration(300)
.attr("y", function(d) {
return h - yScale(d) + 14;
})
.text(function(d) {
return d;
})
// exit selection
texts
.exit().remove();
}
window.onload = draw(myData);
setInterval(function() {
var data = d3.range(5).map(function() {
return parseInt(Math.random() * 20 + 1);
});
update(data);
}, 3000)
<div id="chart"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.js"></script>

d3js updates only once

I have a visualization task that I need to make it done with d3.js. Here's my code.
var w = 700;
var h = 500;
var offset = 100;
var padding = 20;
var colors = d3.scale.category10();
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
var texts = function(ds,ds2){
var stack = d3.layout.stack();
stack_data = stack(ds);
var xScale = d3.scale.ordinal()
.domain(d3.range(ds[0].length))
.rangeRoundBands([0, w-offset], 0.50);
var yScale = d3.scale.linear()
.domain([0,
d3.max(stack_data, function(d) {
return d3.max(d, function(d) {
return d.y0 + d.y -20;
});
})
])
.range([padding, h-50]);
var xAxis = d3.svg.axis()
.scale(xScale)
.orient("bottom")
.ticks(ds[0].length);
gs = svg.selectAll("g").data(stack_data);
for (var i5 = 0; i5 < ds.length; i5++) {
gs.enter()
.append("g")
.attr("class", "stacked_bars")
.attr("fill", function(d, i) {
return colors(i);
});
asd = gs.selectAll("rect").data(function(d) { return d; });
asd.enter().append("rect");
asd.transition()
.duration(1000)
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d.y0) - yScale(d.y);
})
.attr("height", function(d) {
return yScale(d.y);
})
.attr("width", xScale.rangeBand())
.attr("class", "rectbar");
};
gs.append("g") // add a group element to the svg
.attr("class", "axis") //Assign class "axis" to group
.attr("transform", "translate(0," + (h - padding) + ")") // shift the axis to bottom
.call(xAxis); // call the axis function
gs.exit().remove();
}
res = dataGenerator("Europe");
dataset = res[0];
dataset2 = res[1];
texts(dataset,dataset2);
d3.select("#selector").on("change", function() {
cont = d3.select(this).property('value');
res = dataGenerator(cont)
dataset = res[0]
dataset2 = res[1]
//svg.selectAll(".sym").remove()
texts(dataset,dataset2);
});
It basically gets the data and generates stacked bars. When user uses the select element on the page, it updates the data and generates new results. It successfully gets the first results and when user selects another option, it makes it happen also. But when user tries to use select part once again. It only generates bars for dataset's first item.
So, in this particular case I have countries and their data as numbers, at first load and first update it successfully shows all but when it comes to second update, it only generate bars for first country in dataset. It's been hours that I'm trying to fix this. I know I only have a little mistake but couldn't make it to solve.
Also here's the jsfiddle of the code: https://jsfiddle.net/510ep9ux/4/
Since I'm new at d3.js, I may not understand the update concept well.
So, any guesses?
Solved, using two separate functions textsInit and textsUpdate :
https://jsfiddle.net/qxqdp36x/2/
Essentially you need to separate initialization and update logic, and avoid re-creating elements when updating, that causes unintended behaviours.
Also, the variables gs and asd needs to be global to be accessible to both functions.
var textsInit = function(ds, ds2) {
var stack = d3.layout.stack();
stack_data = stack(ds);
var xScale = d3.scale.ordinal()
.domain(d3.range(ds[0].length))
.rangeRoundBands([0, w - offset], 0.50);
var yScale = d3.scale.linear()
.domain([0,
d3.max(stack_data, function(d) {
return d3.max(d, function(d) {
return d.y0 + d.y - 20;
});
})
])
.range([padding, h - 50]);
var xAxis = d3.svg.axis()
.scale(xScale)
.orient("bottom")
.ticks(ds[0].length);
gs = svg.selectAll("g").data(stack_data);
bars = gs.enter();
bars.append("g")
.attr("class", "stacked_bars")
.attr("fill", function(d, i) {
return colors(i);
});
asd = gs.selectAll("rect").data(function(d) {
return d;
});
asd.enter().append("rect");
asd.transition()
.duration(1000)
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d.y0) - yScale(d.y);
})
.attr("height", function(d) {
return yScale(d.y);
})
.attr("width", xScale.rangeBand())
.attr("class", "rectbar");
gs.append("g") // add a group element to the svg
.attr("class", "axis") //Assign class "axis" to group
.attr("transform", "translate(0," + (h - padding) + ")") // shift the axis to bottom
.call(xAxis); // call the axis function
}
And:
var textsUpdate = function(ds, ds2) {
var stack = d3.layout.stack();
stack_data = stack(ds);
var xScale = d3.scale.ordinal()
.domain(d3.range(ds[0].length))
.rangeRoundBands([0, w - offset], 0.50);
var yScale = d3.scale.linear()
.domain([0,
d3.max(stack_data, function(d) {
return d3.max(d, function(d) {
return d.y0 + d.y - 20;
});
})
])
.range([padding, h - 50]);
gs.data(stack_data);
asd = gs.selectAll("rect").data(function(d) { return d; });
asd.transition()
.duration(1000)
.attr("x", function(d, i) {
return xScale(i);
})
.attr("y", function(d) {
return h - yScale(d.y0) - yScale(d.y);
})
.attr("height", function(d) {
return yScale(d.y);
})
.attr("width", xScale.rangeBand())
.attr("class", "rectbar");
}
Edited to fix a small bug, updating the asd selection's data.
I made 2 simple but crucial changes to your code.
https://jsfiddle.net/guanzo/510ep9ux/6/
From
gs = svg.selectAll("g").data(stack_data);
to
gs = svg.selectAll("g.stacked_bars").data(stack_data);
The axis is also contained in a g element, so you have to ensure you're only selecting elements that are used for your data, and not unrelated elements.
From
gs.append("g")
.attr("class", "axis")
.attr("transform", "translate(0," + (h - padding) + ")")
.call(xAxis);
to
svg.append("g")
.attr("class", "axis")
.attr("transform", "translate(0," + (h - padding) + ")")
.call(xAxis);
If you go into the browser inspector you'll see that you have an axis element for EVERY stacked_bars element, you only need 1 obviously. It only looks like there's 1 axis because they're absolutely positioned and stacked on top of each other.
I changed it so that the axis is appended when the svg is created, and every time new data is selected, the axis will update itself.

D3 - Load in and display data, row by row with set delay

I am trying to use time series data to plot bubbles on a map. What I would like to do is slowly plot these bubbles based on their date rather than all at once.
Something similar to:
http://www.nytimes.com/interactive/2014/upshot/mapping-the-spread-of-drought-across-the-us.html?_r=0
Here is some sample data:
date count code,country,lat,lon,counter
1/28/16 3 AND,Andorra,42.5,1.516667,0.577121255
1/29/16,146,ARE,United Arab Emirates,24.46666667,54.366667,2.264352856
1/30/16,13,AFG,Afghanistan,34.51666667,69.183333,1.213943352
Example of D3 Map
I have already looked at MB's tutorials on Path Transitions, Udacity's course on D3, and many questions on Stack Overflow.
I have previously tried using setInterval and setTimeout but most of the examples were with multiple data files. I would like to use one datafile line by line.
Code:
var width = 960,
height = 500;
var projection = d3.geo.mercator()
.center([0, 5 ])
.scale(200)
.rotate([-180,0]);
var tip = d3.tip()
.attr('class', 'd3-tip')
.offset([0, 0])
.html(function(d) {
return "<strong>Frequency:</strong> <span style='color:white'>" + d.count + "</span>"+ "<br/>" + d.country;
})
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var path = d3.geo.path()
.projection(projection);
var g = svg.append("g");
// load and display the World
d3.json("world-110m2.json", function(error, topology) {
svg.call(tip)
// load and display the cities
d3.csv("cities2_or.csv", function(error, data) {
max = d3.max(data, function(d)
{return +d.counter})
coloring = d3.scale.linear()
.domain([0, max])
.range(["blue", "green"])
radiusing = d3.scale.linear()
.domain([0, max])
//.domain([0, 100])
.range([2, 30])
g.selectAll("circle")
.data(data)
.enter()
.append("circle")
.on('mouseover', tip.show)
.on('mouseout', tip.hide)
.attr("cx", function(d) {
return projection([d.lon, d.lat])[0];
})
.attr("cy", function(d) {
return projection([d.lon, d.lat])[1];
})
.style("r", function(d){
return radiusing(+d.counter)
;})
//.style("opacity", .5)
.style("fill", function(d){
return coloring(+d.counter);
})
});
Thanks for any help
I took #adilapapaya suggestions and tried using the delay function but I am only able to plot the first point.
Instead of the g.selectAll that I was using above I have replaced it with the following. This however only plots the first point in my csv file and then stops.
g.append("circle")
.data(data)
.attr("cx", function(d) {
return projection([d.lon, d.lat])[0];
})
.attr("cy", function(d) {
return projection([d.lon, d.lat])[1];
})
.style("r", 20)
.transition()
.duration(1)
.delay(function(d, i) { return i*1; })
.style("r",30)
.style("fill","green");
Thanks to Andrew Guy who helped find the JS fiddle example for me. Worked perfectly. My issue was not using the enter before hand. Here is the final code. Please respond if anyone has any questions.
var width = 960,
height = 500;
var projection = d3.geo.mercator()
.center([0, 5 ])
.scale(200)
.rotate([-180,0]);
var tip = d3.tip()
.attr('class', 'd3-tip')
.offset([0, 0])
.html(function(d) {
return "<strong>Frequency:</strong> <span style='color:white'>" + d.count + "</span>"+ "<br/>" + d.country;
})
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var path = d3.geo.path()
.projection(projection);
var g = svg.append("g");
// load and display the World
d3.json("world-110m2.json", function(error, topology) {
svg.call(tip)
// load and display the cities
d3.csv("cities2_or.csv", function(error, data) {
max = d3.max(data, function(d)
{return +d.counter})
coloring = d3.scale.linear()
.domain([0, max])
.range(["blue", "green"])
radiusing = d3.scale.linear()
.domain([0, max])
//.domain([0, 100])
.range([2, 30])
g.selectAll("circle")
.data(data)
.enter()
.append("circle")
.on('mouseover', tip.show)
.on('mouseout', tip.hide)
.attr("cx", function(d) {
return projection([d.lon, d.lat])[0];
})
.attr("cy", function(d) {
return projection([d.lon, d.lat])[1];
})
// .style("r", function(d){
// return radiusing(+d.counter)
// ;})
//.style("opacity", .5)
.style("fill", function(d){
return coloring(+d.counter);})
.style("r",0)
.transition()
.duration(500)
.delay(function(d, i) { return i*200; })
.style("r",30);
});
g.selectAll("path")
.data(topojson.object(topology, topology.objects.countries)
.geometries)
.enter()
.append("path")
.attr("d", path)
});
// zoom and pan
var zoom = d3.behavior.zoom()
.on("zoom",function() {
g.attr("transform","translate("+
d3.event.translate.join(",")+")scale("+d3.event.scale+")");
g.selectAll("circle")
.attr("d", path.projection(projection));
g.selectAll("path")
.attr("d", path.projection(projection));
});
svg.call(zoom)

D3 updating bar chart with new data set cause update issue

Well the rendering of bar chart works fine with default given data. The problem occurs on the button click which should also cause the get of new data set. Updating the x-axis y-axis works well but the rendering data causes problems.
First Ill try to remove all the previously added rects and then add the new data set. But all the new rect elements gets added into wrong place, because there is no reference to old rects.
Here is the code and the redraw is in the end of code.
http://jsfiddle.net/staar2/wBNWK/9/
var data = JSON.parse('[{"hour":0,"time":147},{"hour":1,"time":0},{"hour":2,"time":74},{"hour":3,"time":141},{"hour":4,"time":137},{"hour":5,"time":210},{"hour":6,"time":71},{"hour":7,"time":73},{"hour":8,"time":0},{"hour":9,"time":68},{"hour":10,"time":70},{"hour":11,"time":0},{"hour":12,"time":147},{"hour":13,"time":0},{"hour":14,"time":0},{"hour":15,"time":69},{"hour":16,"time":67},{"hour":17,"time":67},{"hour":18,"time":66},{"hour":19,"time":0},{"hour":20,"time":0},{"hour":21,"time":66},{"hour":22,"time":210},{"hour":23,"time":0}] ');
var w = 15,
h = 80;
var xScale = d3.scale.linear()
.domain([0, 1])
.range([0, w]);
var yScale = d3.scale.linear()
.domain([0, d3.max(data, function (d) {
return d.time;
})])
.rangeRound([5, h]);
var xAxis = d3.svg.axis()
.scale(xScale)
.orient("bottom")
.ticks(5);
var yAxis = d3.svg.axis()
.scale(yScale)
.orient("left");
var chart = d3.select("#viz")
.append("svg")
.attr("class", "chart")
.attr("width", w * data.length - 1)
.attr("height", h);
chart.selectAll("rect")
.data(data)
.enter().append("rect")
.attr("x", function(d, i) {
return xScale(i) - 0.5;
})
.attr("y", function(d) {
return h - yScale(d.time) - 0.5;
})
.attr("width", w)
.attr("height", function(d) {
return yScale(d.time);
});
chart.selectAll("text")
.data(data)
.enter()
.append("text")
.text(function(d) {
if (d.time > 10) {
return Math.round(d.time);
}
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "#FFF")
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return xScale(i) + w / 2;
})
.attr("y", function(d) {
return h - yScale(d.time) - 0.5 + 10;
});
chart.append("g")
.attr("transform", "translate(0," + (h) + ")")
.call(xAxis);
function redraw() {
// This the part where the incoming data set also changes, which means the update to x-axis y-axis, labels
yScale.domain([0, d3.max(data, function (d) {
return d.time;
})]);
var bars = d3.selectAll("rect")
.data(data, function (d) {
return d.hour;
});
bars
.transition()
.duration(500)
.attr("x", w) // <-- Exit stage left
.remove();
d3.selectAll("rect") // This is actually empty
.data(data, function (d) {
return d.hour;
})
.enter()
.append("rect")
.attr("x", function(d, i) {
console.log(d, d.day, xScale(d.day));
return xScale(d.day);
})
.attr("y", function(d) {
return yScale(d.time);
})
.attr("width", w)
.attr("height", function (d) {
return h - yScale(d.time);
});
}
d3.select("button").on("click", function() {
console.log('Clicked');
redraw();
});
Agree with Sam (although there were a few more issues, like using remove() without exit(), etc.) and I am putting this out because I was playing with it as I was cleaning the code and applying the update pattern. Here is the FIDDLE with changes in code I made. I only changed the first few data points but this should get you going.
var data2 = JSON.parse('[{"hour":0,"time":153},{"hour":1,"time":10},{"hour":2,"time":35},{"hour":3,"time":150},
UPDATE: per request, adding logic to consider an update with new data. UPDATED FIDDLE.
Since you're binding the same data to bars, the enter selection is empty. Once you remove the existing bars, you append a new bar for each data point in the enter selection - which again is empty. If you had different data, the bars should append.
If you haven't read through it already, the general update pattern is a great resource for understanding this sort of thing.

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