getting and using data from CSV file d3 v5 - javascript

I am trying to create a map visualization using d3.
I have gotten the map to work and am trying to add points on the map.
Depending on some other data in the CSV file (inspection results) I want certain points to have a different color.
I can add the points using this code, but I cannot get the colors to come out correctly (there should be red ones, but all of them are green). I think it is a problem with how I'm trying to get the data out, or just a problem with my JavaScript in general. Any help would be appreciated. Thank you!
function colorr(d) {
if (d == 0) {
return "red";
} else {
return "green";
}
}
var dataset = []
// load data about food
// https://stackoverflow.com/questions/47821332/plot-points-in-map-d3-javascript
// https://groups.google.com/forum/#!topic/d3-js/AVEa7nPCFAk
// https://stackoverflow.com/questions/10805184/show-data-on-mouseover-of-circle
d3.csv('data6.csv').then( function(data) {
// don't know if this actually does anything...
dataset=data.map(function(d) { return [+d["InspectionScore"],+d["Longitude"],+d["Latitude"]];});
g.selectAll('circle')
.data(data)
.enter()
.append('circle')
.attr("cx",function(d) { return projection([d.Longitude,d.Latitude])[0]; }).merge(g)
.attr("cy",function(d) { return projection([d.Longitude,d.Latitude])[1]; }).merge(g)
.attr("r", .4)
.attr("fill", d3.color(colorr( function(d) { return d.InspectionScore } ) ));
});

This can be resolved by changing the last line to:
.attr("fill", d => d3.color(colorr(d.InspectionScore))));
The reason this works is that d3's attr allows you to take the attribute value from a function. In this case you want to transform the data element to either red or blue. This is what the arrow function does in the above code. It is equivalent to :
.attr("fill", function(d) {
return d3.color(colorr(d.InspectionScore));
})
To get a deeper understanding of how D3 works, you can check the tutorials.

Related

plotting graph symbols using two-level nested data in d3.js

I am trying to replicate this example of a multiline chart with dots. My data is basically the same, where I have an object with name and values in the first level, and then a couple of values in the second level, inside values. The length of the arrays inside values is 40.
Now, one requirement is that all the dots for all the paths are inside the same g group within the DOM. This is giving me a lot of trouble because I can't seem to figure out how to join the circles with the appropriate portion of the nested data.
The last thing I've tried is this:
var symbolsb = d3.select("#plot-b") // plot-b is the graph area group within the svg
.append("g")
.attr("id", "symbols-b");
symbolsb.selectAll("circle")
.data(games, function(d) {console.log(d.values) // games is my data object
return d.values})
.enter()
.append("circle")
.attr("class", "symbolsb")
.attr("cx", function(d,i) {console.log(d)
return x(d.values.date);})
.attr("cy", function(d,i) {return y_count(d.count);})
.attr("r", function(d,i) {
let parent = this.parentNode;
let datum = d3.select(parent).datum();
console.log(parent)
if (i%3 === 1 && included_names.includes(datum[i].name)) {
return 8;}
else {return null;}})
.style("fill", function(d,i) {
let parent = this.parentNode;
let datum = d3.select(parent).datum();
{return color(datum.name);}});
As I (incorrectly) understand the data() function, I thought that by returning d.values, the functions in cx, cy, and r would just see the array(s) that is inside d.values, but when log d to the console within the functions to define cx, cy, etc. I see again the full object games. Again, I though I should only get the values portion of the object.
I have been able to get a plot that looks like the result I want by loading the data and appending a g when defining symbolsb, but this creates a group for each set of circles.
I think the problem comes from my confusion of how nested objects are accessed by the data() function. So any help explaining that would be greatly appreciated.
It would be great if you could provide a live reproduction, for example in an Observable or VizHub notebook.
This line looks suspect
.data(games, function(d) {console.log(d.values) // games is my data object
return d.values})
The second argument to *selection*.data should be a 'key function', a function that returns a unique string identifier for each datum. Here you are giving an object (d.values) which will get stringified to [object Object] for each data point. This also explains why you're seeing the full games object when logging. I think it's safe here to just remove the second argument to .data():
.data(games)
This also doesn't look right
.attr("r", function(d,i) {
let parent = this.parentNode;
let datum = d3.select(parent).datum();
console.log(parent)
if (i%3 === 1 && included_names.includes(datum[i].name)) {
return 8;}
else {
return null;
*emphasized text*}})
I'm not entirely sure what you're trying to do here. If you're trying to access the name of the data point you can just access it on the data point itself using .attr("r", function(d,i) { if (included_names.includes(d.name)) { return 8 } else { return 0} )

How do I fix this botched transition resulting from missing data in my D3.js line chart?

I have a D3.js line chart that updates when the user chooses a new country. Overall I'm satisfied with the way my chart updates and it looks very clean when two conditions are met:
There is no missing data for either country
Country one has no missing data but country two has missing data.
Here is the problem scenario: country one has missing data but country two has no missing data.
If country one has missing data on the left, when the chart updates, the new segments of the line get appended on the right side (usually on top of the existing segments of the line) and then gradually slide over to the left. It's a very ugly transition and words might not suffice so here are a few pictures.
Country One: Missing data on left
Transition to Country Two (which has no missing data)
Country Two: No missing data
I have a hunch about the source of the problem and how I might be able to fix it.
A potential solution?
This line chart by Mike Bostock is interesting. It has missing data but it uses linear interpolation to fill in the gaps. Would I be able to solve my problem by filling in the gaps like this? I tried implementing this solution but I just can't get the second line for the missing data to appear.
https://observablehq.com/#d3/line-with-missing-data
The Code for my Line Chart
I have two separate functions for my line chart. The render function initializes the chart and then I have to use the update function to transition to new data. I know that's a bit weird but I'm relatively inexperienced with D3.js and I can't get it to work with one function. For the That is another potential problem in and of itself, but I don't think it's causing the botched transition, is it?
For the sake of brevity, I only included the parts where the line gets appended and where it gets updated.
function render(url){
d3.json(url).then(function (data) {
data.forEach(function (d) {
d.Year = +d.Year;
d.Value = +d.Value / 1000;
});
...
...
omitted code
...
...
svg.append("path")
.datum(data)
.attr('id','mainline')
.attr("fill", "none")
.attr("stroke", "steelblue")
.attr("stroke-width", 3)
.attr("d", d3.line()
.defined(d => !isNaN(d.Value))
.x(function (d) {
return x(d.Year)
})
.y(function (d) {
return y(d.Value)
})
);
}
function update(url) {
//Reading in new data and updating values
d3.json(url).then(function (data) {
data.forEach(function (d) {
d.Year = +d.Year;
d.Value = +d.Value / 1000;
});
...
...
omitted code
...
...
var lines = svg.selectAll("#mainline").datum(data).attr("class","line");
lines.transition().ease(d3.easeLinear).duration(1500)
.attr("d", d3.line()
.defined(d => !isNaN(d.Value))
.x(function (d) {
return x(d.Year)
})
.y(function (d) {
return y(d.Value)
})
);
Any help would be greatly appreciated. Thanks!

How to crossfilter histogram and scatterplot matrix in d3 v4?

I am using this kind of scatterplot matrix and a histogram as two views, in d3. Both of them get the data from the same csv file. This is how the histogram looks like (x axis):
To brush the histogram I use the code below, which is similar to this snippet:
svg.append("g")
.attr("class", "brush")
.call(d3.brushX()
.on("end", brushed));
function brushed() {
if (!d3.event.sourceEvent) return;
if (!d3.event.selection) return;
var d0 = d3.event.selection.map(x.invert),
d1 = [Math.floor(d0[0]*10)/10, Math.ceil(d0[1]*10)/10];
if (d1[0] >= d1[1]) {
d1[0] = Math.floor(d0[0]);
d1[1] = d1[0]+0.1;
}
d3.select(this).transition().call(d3.event.target.move, d1.map(x));
}
How can I link the two views, so that when I brush the histogram, the scatterplot matrix will show the brushed points as colored in red, and the other points as, lets say, grey?
This can get you started:
3 html files:
2 for the visuals (histogram.html and scatter.html)
1 to hold them in iframes (both.html):
Dependency:
jQuery (add to all 3 files)
Create table with 2 cells in both.html:
Add iframes to each cell:
<iframe id='histo_frame' width='100%' height='600px' src='histo.html'></iframe>
<iframe id='scatter_frame' width='100%' height='600px' src='scatter.html'></iframe>
I am using this histogram, and this scatterplot.
Add the linky_dink function to call the function inside your scatter.html (see below...):
function linky_dink(linked_data) {
document.getElementById('scatter_frame').contentWindow.color_by_value(linked_data);
}
In your scatter.html change your cell.selectAll function to this:
cell.selectAll("circle")
.data(data)
.enter().append("circle")
.attr("cx", function(d) { return x(d[p.x]); })
.attr("cy", function(d) { return y(d[p.y]); })
.attr("r", 4)
.attr('data-x', function(d) { return d.frequency }) // get x value being plotted
.attr('data-y', function(d) { return d.year }) // get y value being plotted
.attr("class", "all_circles") // add custom class
.style("fill", function(d) { return color(d.species); });
}
Note the added lines in bold:
Now our histogram circle elements retain the x and y values, along with a custom class we can use for targeting.
Create a color_by_value function:
function color_by_value(passed_value) {
$('.all_circles').each(function(d, val) {
if(Number($(this).attr('data-x')) == passed_value) {
$(this).css({ fill: "#ff0000" })
}
});
}
We know from above this function will be called from the linky_dink function of the parent html file. If the passed value matches that of the circle it will be recolored to #ff0000.
Finally, look for the brushend() function inside your histogram.html file. Find where it says: d3.selectAll("rect.bar").style("opacity", function(d, i) { .... and change to:
d3.selectAll("rect.bar").style("opacity", function(d, i) {
if(d.x >= localBrushYearStart && d.x <= localBrushYearEnd || brush.empty()) {
parent.linky_dink(d.y)
return(1)
} else {
return(.4)
}
});
Now, in addition to controlling the rect opacity on brushing, we are also calling our linky_dink function in our both.html file, thus passing any brushed histogram value onto the scatterplot matrix for recoloring.
Result:
Not the greatest solution for obvious reasons. It only recolors the scatterplot when the brushing ends. It targets circles by sweeping over all classes which is horribly inefficient. The colored circles are not uncolored when the brushing leaves those values since this overwhelms the linky_dink function. And I imagine you'd rather not use iframes, let alone 3 independent files. Finally, jQuery isn't really needed as D3 provides the needed functionality. But there was also no posted solution, so perhaps this will help you or someone else come up with a better answer.

d3 v4: merge enter and update selections to remove duplicate code

I understand that merge can be used to combine enter and update selections in d3 v4, as in the simple example here: https://bl.ocks.org/mbostock/3808218.
I have a scatter plot in which multiple variables are displayed on a shared x-axis, for different groups selected by a dropdown box. When a new group is selected, the overall set of datapoints is updated, with points for each variable added like this:
.each(function(d, i) {
var min = d3.min(d.values, function(d) { return d.value; } );
var max = d3.max(d.values, function(d) { return d.value; } );
// Join new data with old elements
var points = d3.select(this).selectAll("circle")
.data(d.values, function(d) { return (d.Plot); } );
// Add new elements
points.enter().append("circle")
.attr("cy", y(d.key))
.attr("r", 10)
.style("opacity", 0.5)
.style("fill", function(d) { return elevColor(d.Elevation); })
.merge(points) //(?)
.transition()
.attr("cx", function(d) { return x((d.value-min)/(max-min)); });
// Remove old elements not present in new data
points.exit().remove();
This whole piece of code is largely duplicated for the overall enter selection and again in the overall update selection (as opposed to the individual variables), which seems less than ideal. How would merge be used to to remove this duplicated code?
The full example is here: http://plnkr.co/edit/VE0CtevC3XSCpeLtJmxq?p=preview
I'm the author of the solution for your past question, which you linked in this one. I provided that solution in a comment, not as a proper answer, because I was in a hurry and I wrote a lazy solution, full of duplication — as you say here. As I commented in the same question, the solution for reducing the duplication is using merge.
Right now, in your code, there is duplication regarding the setup of the "update" and "enter" selections:
var update = g.selectAll(".datapoints")
.data(filtered[0].values);
var enter = update.enter().append("g")
.attr("class", "datapoints");
update.each(function(d, i){
//code here
});
enter.each(function(d, i){
//same code here
});
To avoid the duplication, we merge the selections. This is how you can do it:
var enter = update.enter().append("g")
.attr("class", "datapoints")
.merge(update)
.each(function(d, i) {
//etc...
Here is the updated Plunker: http://plnkr.co/edit/MADPLmfiqpLSj9aGK8SC?p=preview

How to add links from CSV file to SVG elements generated with D3?

I am in a bit of a bind and need some with help with linking my svg elements with URL's contained in an CSV file. I have a symbols map with over 100 symbols. The symbols are based on coordinates pulled from longitude and latitude in a CSV file which also contains the links that I would like each unique symbol to link to. I know there is an easy way to do this, pretty sure I'm overlooking the solution.
My CSV file is as follows:
name,longitude,latitude,city,state,url
College of Charleston,803,342,Charleston,SC,http://sitename.com/colleges/college-of-charleston/
etc...
My symbols are generated using D3 and placed on top of my SVG map. I am also using D3 to wrap the symbols in anchor tags. I simply want these anchor tags to link to the appropriate url that correlates with the latitude and longitudes of that particular symbol.
/* Start SVG */
var width = 960,
height = 640.4,
positions = [],
centered;
var bodyNode = d3.select('#Map').node();
var list = $('.school-list').each(function(i){});
var svg = d3.select("#Map");
var contain = d3.select("#map-contain");
var circles = svg.append("svg:g")
.attr("id", "circles");
var g = d3.selectAll("g");
// var locationBySchools = {};
d3.csv("http://sitename.com/wp-content/themes/vibe/homepage/schools.csv",function(schools){
schools = schools.filter(function(schools){
var location = [+schools.longitude, +schools.latitude];
// locationBySchools[schools.loc] = location;
positions.push(location);
return true;
});
circles.selectAll("circles")
.data(schools)
.enter().append("svg:a")
.attr("xlink:href", function(d) { })
.append("svg:circle")
.attr("cx", function(d,i) {return positions[i][0]})
.attr("cy", function(d,i) {return positions[i][1]})
.attr("r", function(d,i) {return 6})
.attr("i", function(d,i) {return i})
.attr("class", "symbol")
Really stuck with this one...Any ideas?
The short answer is that you should simply return the url property from your data when you are assigning the xlink:href attribute:
.attr("xlink:href", function(d) { return d.url; })
However, there are a couple other issues with the code you posted.
Issue 1. circles.selectAll('circles')
This starts with a the selection of your g element, and within it, selects all elements with the tag-name circles. The problem is that circles is not a valid svg tag. This just creates an empty selection, which is okay in this case because the selection is only being used to create new elements. But, it's a bad habit to make dummy selections like this, and it can be confusing to others trying to understand your code. Instead, you should decide on a class name to give to each of the new link elements, and use that class name to make your selection. For example, if you decide to give them a class of link you would want to do the following:
First create a selection for all of the elements with class="link":
circles.selectAll('.link')
This selection will initially be empty, but when you use .data() to bind your data to it, it will be given an enter selection which you can use to create the new elements. Then you can add the class of link to the newly created elements:
.data(schools).enter().append('svg:a')
.attr('class', 'link')
Issue 2. .attr("i", function(d,i) {return i})
This one's pretty straightforward, there is no such attribute as i on svg elements. If you want to store arbitrary data on an element to be able to access it later, you can use a data attribute. In this case you might want to use something nice and semantic like data-index.
Issue 3. positions.push(location)
This is a big one. I would not recommend that you make a separate array to store the altered values from your dataset. You can use an accessor function in your d3.csv() function call, and clean up the incoming data that way. It will save you from having to maintain consistent data across two separate arrays. The accessor function will iterate over the dataset, taking as input the current datum, and should return an object representing the adjusted datum that will be used. This is a good spot to use your unary operator to coerce your latitude and longitude:
function accessor(d) {
return {
name: d.name,
longitude: +d.longitude,
latitude: +d.latitude,
city: d.city,
state: d.state,
url: d.url
};
}
There are two different ways to hook the accessor function into your d3.csv() call:
Method 1: Add a middle parameter to d3.csv() so that the parameters are (<url>, <accessor>, <callback>):
d3.csv('path/to/schools.csv', accessor, function(schools) {
// ...etc...
});
Method 2: Use the .row() method of d3.csv()
d3.csv('path/to/schools.csv')
.row(accessor)
.get(function(schools) {
// ...etc...
});
Now when you want to access the latitude and longitude in your preferred format, you can get them right from the bound data, instead of from an outside source. This keeps everything clean and consistent.
Putting all of this together, you get the following:
d3.csv('http://sitename.com/wp-content/themes/vibe/homepage/schools.csv')
// provide the accessor function
.row(function accessor(d) {
return {
name: d.name,
longitude: +d.longitude,
latitude: +d.latitude,
city: d.city,
state: d.state,
url: d.url
};
})
// provide a callback function
.get(function callback(schools) {
circles.selectAll('.link')
.data(schools)
.enter().append('svg:a')
.attr('class', 'link')
// point the link to the url from the data
.attr('xlink:href', function(d) { return d.url; })
.append('svg:circle')
.attr('class', 'symbol')
// now we can just use longitude and latitude
// since we cleaned them up in the accessor fn
.attr('cx', function(d) { return d.longitude; })
.attr('cy', function(d) { return d.latitude; })
// constants can be assigned directly
.attr('r', 6)
.attr('data-index', function(d,i) { return i; });
});

Categories