simple d3 line chart... need the line to span the whole svg and the labels to be anchored to the path line itself. bonus points if there's optional code to add markers as well. thanks in advance.
<html>
<head>
<script src="https://d3js.org/d3.v5.min.js"></script>
<script>
function createLineChart(data,id) {
var svg = d3.select("body").append("svg")
.attr("width", 800)
.attr("height", 600);
var line = d3.line()
.x(function(d, i) { return i * 50 + 50; })
.y(function(d) { return 300 - d; });
svg.append("path")
.datum(data)
.attr("d", line)
.attr("stroke", "black")
.attr("stroke-width", 2)
.attr("fill", "none");
data.forEach(function(d, i) {
if (i > 0) {
var percentChange = (d - data[i - 1]) / data[i - 1] * 100;
var color = percentChange >= 0 ? "green" : "red";
var y = percentChange >= 0 ? d - 15 : d + 15;
svg.append("text")
.text(percentChange.toFixed(1) + "%")
.attr("x", i * 50 + 50)
.attr("y", y)
.attr("text-anchor", "middle")
.attr("fill", color);
}
});
}
</script>
</head>
<body>
</body>
<script>
var data = [10, 20, 15, 40, 50, 60];
createLineChart(data);
</script>
</html>
I guess the main things you need to read up on are d3 scales and selections (particularly joins). In particular:
We'll define the width w and height h of the SVG and then defining scales to fit the path into the SVG.
We'll use the data to define each of the path, markers, and text in terms of the data.
createLineChart([10, 20, 15, 40, 50, 60], { mark_points: true })
function createLineChart(data, opts = {}) {
let { w = 800, h = 500, mark_points = false } = opts;
let pad = 50;
let x_scale = d3
.scaleLinear()
.domain([0, data.length - 1])
.range([pad, w - pad]);
let [ymin, ymax] = d3.extent(data);
let y_scale = d3
.scaleLinear()
.domain([ymin, ymax])
.range([h - pad, pad]);
let svg = d3.select('#container')
.append("svg")
.attr("width", w)
.attr("height", h)
.style("border", "solid 1px black");
let line = d3
.line()
.x(function (d, i) {
return x_scale(i);
})
.y(function (d) {
return y_scale(d);
});
svg
.append("path")
.datum(data)
.attr("d", line)
.attr("stroke", "black")
.attr("stroke-width", 2)
.attr("fill", "none");
svg
.selectAll("circle")
.data(data)
.join("circle")
.attr("cx", (_, i) => x_scale(i))
.attr("cy", (d) => y_scale(d))
.attr("r", 5)
.attr("fill", "black");
if (mark_points) {
svg
.selectAll("text")
.data(data)
.join("text")
.attr("x", (_, i) => x_scale(i))
.attr("y", (d) => y_scale(d))
.attr("dx", -3)
.attr("dy", 12)
.attr("font-size", 16)
.attr("text-anchor", "end")
.attr("fill", (_, i) =>
data[i] < data[i - 1]
? "red"
: data[i] == data[i - 1]
? "blue"
: "green"
)
.text(function (_, i) {
if (i > 0) {
let change = (data[i] - data[i - 1]) / data[i - 1];
return d3.format("0.2%")(change);
} else {
return "";
}
});
}
svg
.append("g")
.attr("transform", `translate(0, ${h - pad})`)
.call(d3.axisBottom(x_scale).ticks(data.length));
svg
.append("g")
.attr("transform", `translate(${pad})`)
.call(d3.axisLeft(y_scale).ticks(5));
}
<script src="https://d3js.org/d3.v7.min.js"></script>
<div id="container"></div>
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>
I'm wanting to recreate this graph
<div class="discrete" data-value="1,0,1,0,0,1,0,0,1,1,1,1,1,0,1,0,1,1,1,1"></div>
For each 1 I want to make a top half line, and 0 the opposite.
function discreteChart(self, dataset) {
var w = parseInt(d3.select(self).style("width")),
h = parseInt(d3.select(self).style("height")),
svg = d3.select(self)
.append("svg")
.attr("width", w)
.attr("height", h),
yScale = d3.scale
.linear()
.domain([0, d3.max(dataset)])
.range([0, h]);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr('fill', '#363636')
.attr('rx', '1')
.attr('ry', '1')
.attr("x", function(d, i) {
return i * 3;
})
.attr("y", function(d) {
return h - yScale(d) / 1;
})
.attr("width", 1) // width of bar
.attr("height", function(d) {
return yScale(d);
});
}
My problem is I'm not entirely sure how to do this. I have the rectangles made but I can't place them into position.
http://jsfiddle.net/everina/1eec20xe/
You can make line instead of rectangle as pointed by Anko.
Here is how you can make a line:
svg.selectAll("line")
.data(dataset)
.enter()
.append("line")
.attr('stroke', '#363636')
.attr('x1', function(d, i) {
return (i + 1) * 10;//xposition of line
})
.attr('x2', function(d, i) {
return (i + 1) * 10;
})
.attr('y1', function(d, i) {
return 10;//starting point of line
})
.attr('y2', function(d, i) {
if (d) {
return 0; //if 0 then line should be below
} else {
return 20;//if non 0 then line should be above
}
})
working example here
Hope this helps!
If you want to make the chart scaleable, so the positions are correct for any height:
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr('fill', '#363636')
.attr('rx', '1')
.attr('ry', '1')
.attr("x", function(d, i) {
return i * 3;
})
.attr("y", function(d) {
return d ? h / 2 : 0;
})
.attr("width", 1) // width of bar
.attr("height", function(d) {
return h/2;
});
I've followed the tutorial to make a bar chart from Scott Murray from alignedleft. I'm having problem with my dataset and adding the dataset to a bar as text.
The image below: 1 bar chart: from the tutorial , 2nd bar chart: how I want to display the text.
Here's my code so far:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Tutorial d3 bar chart!</title>
<script type="text/javascript" src="d3/d3.v3.js"></script>
</head>
<body>
<script type="text/javascript">
//Width and height
var w = 500;
var h = 100;
var i = 0;
var barPadding = 1;
var dataset = [
{key:"Department1", value:6234490},
{key:"Department 2", value:9700},
{key:"Department 3", value:2954},
];
//Width and height
var w = 500;
var h = 100;
var barPadding = 1;
//Create SVG element
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", function(d, i) {
return i * (w / dataset.length);
})
.attr("y", function(d) {
return h - (d * 4);
})
.attr("width", w / dataset.length - barPadding)
.attr("height", function(d) {
return d * 4;
})
.attr("fill", function(d) {
return "rgb(0, 0, " + (d * 10) + ")";
});
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) {
for(int i = 0; i < dataset.length; i++){
return d[i].key;
}
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return i * (w / dataset.length) + (w / dataset.length - barPadding) / 2;
})
.attr("y", function(d) {
return h - (d * 4) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
</script>
</body>
</html>
I've tried to add the text in this part:
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) {
for(int i = 0; i < dataset.length; i++){
return d[i].key;
}
})
But that just gives me this error:
I hope you guys can help me out.
Try changing int to var, int doesn't exist in javascript.
Every function in d3js provides access to data and the index.
Just use this
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d){return d.key;}
})
EDIT
svg.selectAll("g")
.data(dataset)
.enter()
.append("g")
.append("rect")
.attr("x", function(d, i) {
return i * (w / dataset.length);
})
.attr("y", function(d) {
return h - (d * 4);
})
.attr("width", w / dataset.length - barPadding)
.attr("height", function(d) {
return d * 4;
})
.attr("fill", function(d) {
return "rgb(0, 0, " + (d * 10) + ")";
})
.append("text")
.text(function(d) {
return d.key;
})
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return i * (w / dataset.length) + (w / dataset.length - barPadding) / 2;
})
.attr("y", function(d) {
return h - (d * 4) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white");
I have a d3.js barplot using some json data containing 12 elements. The data value I'm using for bar height is fpkm. I'm able to return that value as a callback to d3's data function- but only for half the elements.
My problem is that only the first half of the values are appearing in my barplot. I only get 6 rows corresponding to my first 6 values.
I made a fiddle here: http://jsfiddle.net/z9Mvt/
I can't seem to figure out why it's only using half the elements in my json.
Any help = appreciated.
html:
<div align='center' id="GECGplot" style='width:98%;text-align:center;'></plot>
and the js:
var gecgData= {"nodeName":"GECG","children":[{"nodeName":0,"nodeData":{"id":"643139","library_id":"SI_5589","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"1.1241","fpkm_conf_lo":"0.898502","fpkm_conf_hi":"1.34969","fpkm_status":"OK","fpkm_percentile_compendium":"8.33","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":1,"nodeData":{"id":"872561","library_id":"SI_5596","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"1.12666","fpkm_conf_lo":"0.871059","fpkm_conf_hi":"1.38226","fpkm_status":"OK","fpkm_percentile_compendium":"16.67","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":2,"nodeData":{"id":"1031623","library_id":"SI_5553","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"1.21305","fpkm_conf_lo":"0.949369","fpkm_conf_hi":"1.47674","fpkm_status":"OK","fpkm_percentile_compendium":"25.00","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":3,"nodeData":{"id":"248423","library_id":"SI_5486","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"1.98203","fpkm_conf_lo":"1.64888","fpkm_conf_hi":"2.31519","fpkm_status":"OK","fpkm_percentile_compendium":"33.33","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":4,"nodeData":{"id":"1039674","library_id":"SI_5554","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"2.24514","fpkm_conf_lo":"1.83333","fpkm_conf_hi":"2.65696","fpkm_status":"OK","fpkm_percentile_compendium":"41.67","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":5,"nodeData":{"id":"304849","library_id":"SI_5485","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"2.29868","fpkm_conf_lo":"2.02514","fpkm_conf_hi":"2.57221","fpkm_status":"OK","fpkm_percentile_compendium":"50.00","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":6,"nodeData":{"id":"417495","library_id":"SI_5484","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"2.61196","fpkm_conf_lo":"2.28949","fpkm_conf_hi":"2.93442","fpkm_status":"OK","fpkm_percentile_compendium":"58.33","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":7,"nodeData":{"id":"928522","library_id":"SI_5595","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"2.94397","fpkm_conf_lo":"2.61962","fpkm_conf_hi":"3.26832","fpkm_status":"OK","fpkm_percentile_compendium":"66.67","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":8,"nodeData":{"id":"622876","library_id":"SI_5552","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"3.27303","fpkm_conf_lo":"2.79509","fpkm_conf_hi":"3.75097","fpkm_status":"OK","fpkm_percentile_compendium":"75.00","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":9,"nodeData":{"id":"50230","library_id":"SI_5487","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"9.88611","fpkm_conf_lo":"8.6495","fpkm_conf_hi":"11.1227","fpkm_status":"OK","fpkm_percentile_compendium":"83.33","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":10,"nodeData":{"id":"816444","library_id":"SI_5594","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"15.1868","fpkm_conf_lo":"13.8218","fpkm_conf_hi":"16.5519","fpkm_status":"OK","fpkm_percentile_compendium":"91.67","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}},
{"nodeName":11,"nodeData":{"id":"496931","library_id":"SI_5551","gene_id":"ENSG00000157554","gene_short_name":"ERG","fpkm":"52.249","fpkm_conf_lo":"50.8217","fpkm_conf_hi":"53.6763","fpkm_status":"OK","fpkm_percentile_compendium":"100.00","chr_id":"21","start":"39751948","end":"40033704","locus":"21:39751948-40033704","report":"0","tracking_id":null,"class_code":null,"nearest_ref":null,"tss_id":null,"length":null,"coverage":null,"fpkm_percentile_origin_tissue":null,"fpkm_percentile_collection_tissue":null,"fpkm_percentile_sample_cancer":null,"fpkm_fold_change_benign":null}}]}
;
//Width and height
// var w = $('#GECGplot').width();
var w = 700;
var h = 300;
var barPadding = 1;
var margin = {top: 40, right: 10, bottom: 20, left: 10};
var xScale = d3.scale.linear().
domain([0, 20]). // your data minimum and maximum
range([0, h]); // the pixels to map to, e.g., the width of the diagram.
//Create SVG element
var svg = d3.select("#GECGplot")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
// .data(dataset)
.data(function(d, i) {
return plotData[i].nodeData.fpkm;
})
.enter()
.append("rect")
.attr("x", function(d, i) {
// alert(plotData.length);
return i * (w / plotData.length);
})
.attr("y", function(d, i) {
alert(plotData[i].nodeData.fpkm);
return h - (plotData[i].nodeData.fpkm * 50); //Height minus data value
})
.attr("width", w / plotData.length - barPadding)
.attr("height", function(d, i) {
return plotData[i].nodeData.fpkm * 50; //Just the data value
})
.attr("fill", function(d, i) {
return "rgb(0, 0, " + (plotData[i].nodeData.fpkm * 50) + ")";
})
svg.selectAll("text")
.data(function(d, i) {
return plotData[i].nodeData.fpkm;
})
.enter()
.append("text")
.text(function(d, i) {
return plotData[i].nodeData.fpkm;
})
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white")
.attr("text-anchor", "middle")
.attr("x", function(d, i) {
return i * (w / plotData.length) + (w / plotData.length - barPadding) / 2;
})
.attr("y", function(d, i) {
return h - (plotData[i].nodeData.fpkm * 50) + 14;
})
// alert(tableSchema);
Here you go. You bind the array "children" to the rectangle elements so you dont need the argument 'i' to access the value you need.
Also, I would recommend using the d3.scale.ordinal() for your x axis as opposed to calculating it explicitly from the data. Litte more flexible.
http://jsfiddle.net/Cef4D/
svg.selectAll("rect")
.data(plotData)
.enter().append("rect")
.attr("x", function(d, i) {return i * (w / plotData.length);})
.attr("y", function(d) {
return h - (d.nodeData.fpkm * 50); //Height minus data value
})
.attr("width", w / plotData.length - barPadding)
.attr("height", function(d, i) {
return d.nodeData.fpkm * 50; //Just the data value
})
.attr("fill", function(d, i) {
return "rgb(0, 0, " + (d.nodeData.fpkm * 50) + ")";
})