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How can I define map extent based on points displayed?

I have the following map I've made, by overlaying points on a mapbox map using d3.js.
I'm trying to get the map to zoom so that the map extent just includes the d3 markers (points).
I think the pseudocode would look something like this:
//find the northernmost, easternmost, southernmost, westernmost points in the data
//get some sort of bounding box?
//make map extent the bounding box?
Existing code:
<div id="map"></div>
<script>
mapboxgl.accessToken = "YOUR_TOKEN";
var map = new mapboxgl.Map({
container: "map",
style: "mapbox://styles/mapbox/streets-v9",
center: [-74.5, 40.0],
zoom: 9
});
var container = map.getCanvasContainer();
var svg = d3
.select(container)
.append("svg")
.attr("width", "100%")
.attr("height", "500")
.style("position", "absolute")
.style("z-index", 2);
function project(d) {
return map.project(new mapboxgl.LngLat(d[0], d[1]));
}
#Lat, long, and value
var data = [
[-74.5, 40.05, 23],
[-74.45, 40.0, 56],
[-74.55, 40.0, 1],
[-74.85, 40.0, 500],
];
var dots = svg
.selectAll("circle")
.data(data)
.enter()
.append("circle")
.attr("r", 20)
.style("fill", "#ff0000");
function render() {
dots
.attr("cx", function (d) {
return project(d).x;
})
.attr("cy", function (d) {
return project(d).y;
});
}
map.on("viewreset", render);
map.on("move", render);
map.on("moveend", render);
render(); // Call once to render
</script>
Update
I found this code for reference, linked here at https://data-map-d3.readthedocs.io/en/latest/steps/step_03.html:
function calculateScaleCenter(features) {
// Get the bounding box of the paths (in pixels!) and calculate a
// scale factor based on the size of the bounding box and the map
// size.
var bbox_path = path.bounds(features),
scale = 0.95 / Math.max(
(bbox_path[1][0] - bbox_path[0][0]) / width,
(bbox_path[1][1] - bbox_path[0][1]) / height
);
// Get the bounding box of the features (in map units!) and use it
// to calculate the center of the features.
var bbox_feature = d3.geo.bounds(features),
center = [
(bbox_feature[1][0] + bbox_feature[0][0]) / 2,
(bbox_feature[1][1] + bbox_feature[0][1]) / 2];
return {
'scale': scale,
'center': center
};
}
However, when I run the function:
var scaleCenter = calculateScaleCenter(data);
console.log("scalecenter is", scaleCenter)
I get the error:
path is not defined
Furthermore, it seems like I would need to dynamically adjust the center and zoom parameters of the mapbox map. Would I just set these values dynamically with the values produced by the calculateScaleCenter function?

The readthedocs example code is erroneously missing a bit of code
Your javascript code is reporting that you have not defined the variable path before using it. You have copied it correctly from readthedocs, but the code you are copying contains an omission.
Fortunately, on the readthedocs version of the code snippet, there is a mention of a Stack Overflow answer http://stackoverflow.com/a/17067379/841644
that gives more information.
Does adding this information, or something similar corresponding to your situation, help fix your problem?
var projection = d3.geo.mercator()
.scale(1);
var path = d3.geo.path()
.projection(projection);

d3-attrTween with custom function.(What did I misunderstand about tween function?)

I have a question about attrTween (sometimes tween()).
I understood custom tween function as
after " attrTween('d' " argument,
I define the custom function.
So, I wrote the custom function as below.
d3.selectAll('circle#circles1')
.transition()
.attrTween('d',function(){
let interpolator=d3.interpolateArray(sdata.vader,sdata1.vader);
return function(t){
return d3.select(this).attr('cy',interpolator(t))
}
})
What I intended is
For All the circles I drew, makes a transition. The transition
is attrTween. The changes is based on data array tied into the
circles. Original data array is sdata and the cy value in the
sdata is sdata.vader. And the transition is heading toward
sdata1.and cy value for sdata1 is sdata1.vader.
To access all the cy value for every single circle, I used
d3.select(this).attr('cy')
However, no error message is shown but no animation was made either.
What did I misunderstand for the custom tween function?
Can anyone help me to fix this code?
Thank you inadvance.
Full code is in the following link.
https://codepen.io/jotnajoa/pen/WNQeEBE

There are multiple problems in the example code, which is not minimal. Providing a minimal, reproducible example would really help solve the problems.
usage of HTML Id to multiple elements.
In HTML, and id attribute must be unique. Here, ids are assigned to groups of circles. A class attribute should be used for this purpose, not an id.
.attr('id','circles1')
should be:
.attr('class','circles1')
Accordingly, the attrTween should lookup the circles with class circle1, rather than the unique circle with id #circle1
d3.selectAll('circle#circles1')
should be
d3.selectAll('.circles1')
Id (or class) assigned in the wrong place.
The circles1 class is assigned before the creation of the circle, hence the instructions applies to an empty selection. The class attribute should be set right after circles have been created.
.attr('id','circles1')
.enter()
.append('circle')
should be
.enter()
.append('circle')
.attr('class','circles1')
Wrong attribute tweened
The attribute to transition is the circle's cy attribute, not a path's d attribute. Hence
.attrTween('d',function(){
should be
.attrTween('cy',function(){
Wrong data interpolated
sdata.vader and sdata1.vader do not exist, sdata and sdata1 seem to be arrays of objects, which in turn do have a vader property.
You probably want d.vader, and the corresponding .vader in sdata1, which would be sdata1[i].vader, in case items are the same order in both arrays.
Interpolating original measures instead of coordinates.
cy is originally defined as:
height-yscale(d.vader)
In the interpolator function, the scale function should also be used.
The attrTween function calls becomes:
.attrTween('cy',function(d, i){
//console.log( i, height-yscale(d.vader), height-yscale(sdata1[i].vader))
let interpolator=d3.interpolateArray(height-yscale(d.vader), height-yscale(sdata1[i].vader));
return function(t) { return interpolator(t)}
})
Using attrTween where not needed.
Simply transitioning the circles with attr is sufficient for this use case, there is no need to define an interpolator.
d3 will move the position of circles from the original position to the destination, interpolating implicitly.
d3.selectAll('.circles1')
.transition()
.duration(2000)
.attr('cy',function(d, i){
return height-yscale(sdata1[i].vader)
})
I added a long duration for demo purpose, to make obvious that the circles move to the correct location. Once in their final position, they disappear, because they are under the pink circles.
P.S. Same set of corrections is applicable to circles2 set whenever relevant.
Demo of the solution in the snippet below, as codepen does not allow to save modifications without creating an account.
var svg;
var xscale;
var yscale;
var sdata;
var xAxis;
var yAxis;
var width=1500;
var height=500;
var margin=50;
var duration =250;
var vader ='vader'
var textblob='textblob'
var delay =5000;
var tbtrue=false;
var areas
var circles1,circles2;
var sdata1,sdata2
d3.csv('https://raw.githubusercontent.com/jotnajoa/Javascript/master/tweetdata.csv').then(function(data){
svg=d3.select('body').append('svg').attr('width',width).attr('height',height)
var parser = d3.timeParse("%m/%d/%y")
// data를 처리했고, date parser 하는 법 다시한번 명심하자.
sdata = data;
sdata.forEach(function(d){
d.vader = +d.vader;
d.textblob= + d.textblob;
d.date=parser(d.date)
})
// scale을 정해야 함. 나중에 brushable한 범위로 고쳐야함. nice()안하면 정렬도안되고, 첫번째 엔트리 미싱이고
// 난리도 아님.
xscale=d3.scaleTime()
.domain(d3.extent(sdata, function(d) {return d.date }))
.range([0,width*9/10])
.nice()
yscale =d3.scaleLinear()
.domain(d3.extent([-1,1]))
.range([height*4/5,height*1/5])
.nice()
//yaxis는 필요 없을 것 같은데.
//캔버스에 축을 그려야 함 단, translate해서 중간에 걸치게 해야함.
svg.append('g').attr('class','xaxis')
.call(d3.axisBottom(xscale))
.attr('transform','translate('+margin+','+height*1/2+')')
//sdata plotting
var circles = svg.append('g').attr('class','circles')
var area = svg.append('g').attr('class','pathline')
firststage();
//generator로 데이터를 하나씩 떨어뜨리도록 한다.
function firststage(){
function* vaderdropping(data){
for( let i=0;i<data.length;i++){
if( i%50==0) yield svg.node();
let cx = margin+xscale(data[i].date)
let cy = height-yscale(data[i].vader)
circles.append('circle')
.attr('cx',cx)
.attr('cy',0)
.transition()
.duration(duration)
.ease(d3.easeBounce)
.attr('cy',cy)
.attr('r',3)
.style('fill','rgba(230, 99, 99, 0.528)')
}
yield svg.node()
}
//generator 돌리는 부분
let vadergen = vaderdropping(sdata);
let result = vadergen.next()
let interval = setInterval(function(){
if(!result.done) {
vadergen.next();
}
else {
clearInterval(interval)
}
}, 100);
setTimeout(secondstage,5000)
}
function secondstage(){
function* textblobdropping(data){
for( let i=0;i<data.length;i++){
if( i%50==0) yield svg.node();
let cx = margin+xscale(data[i].date)
let cy = height-yscale(data[i].textblob)
circles.append('circle')
.attr('cx',cx)
.attr('cy',0)
.transition()
.duration(duration)
.ease(d3.easeBounce)
.attr('cy',cy)
.attr('r',3)
.style('fill','rgba(112, 99, 230, 0.528)')
}
yield svg.node()
}
//generator 돌리는 부분
let textblobgen = textblobdropping(sdata);
let tresult = textblobgen.next()
let tinterval = setInterval(function(){
if(!tresult.done) {
textblobgen.next();
}
else {
clearInterval(tinterval)
}
}, 100);
setTimeout(thirdstage,2500)
}
function thirdstage(){
//진동을 만들기 위해서,
//베이다와 텍스트 블랍 값을 플립한거다 (제발 워크 아웃하길...)
//그 다음 트윈으로 sdata 와 sdata1을 왔다갔다 하게하면 되지않을까?
sdata1 = sdata.map(function(x){
var y={};
y['date']=x.date;
y['vader']=x.textblob;
y['textblob']=x.vader;
return y});
sdata2 = sdata.map(function(x){
var y={};
y['date']=x.date;
y['vader']=0;
y['textblob']=0;
return y});
d3.selectAll('circle').transition()
.duration(3500)
.style('fill','rgba(1, 1, 1, 0.228)')
//areas는 일종의 함수다, 에리아에다가 데이터를 먹이면,
//에리아를 그리는 역할을 하는것임.
areas = d3.area()
.x(function(d){return margin+xscale(d.date)})
.y0(function(d){return height-yscale(d.vader)})
.y1(function(d){return height-yscale(d.textblob)})
.curve(d3.curveCardinal)
//이렇게 하지말고, sdata2도 만들었으니까 2->1->0 반복하는
// 무한반복 on('end','repeat') loop를 만들어보자.
var uarea=area.append('path')
setTimeout(repeat,500)
function repeat(){
uarea
.style('fill','rgba(112, 99, 230, 0.4)')
.attr('d', areas(sdata))
.transition()
.duration(500)
.attrTween('d',function(){
var interpolator=d3.interpolateArray(sdata,sdata1);
return function(t){
return areas(interpolator(t))
}
})
.transition()
.duration(500)
.attrTween('d',function(){
var interpolator=d3.interpolateArray(sdata1,sdata2);
return function(t){
return areas(interpolator(t))
}
})
.transition()
.duration(500)
.attrTween('d',function(){
var interpolator=d3.interpolateArray(sdata2,sdata);
return function(t){
return areas(interpolator(t))
}
})
.on('end',repeat)
}
setTimeout(fourthstage,500)
}
function fourthstage(){
// console.log(d3.selectAll('circle#circles1').node())
circles1=svg.append('g').selectAll('circle').data(sdata)
.enter().append('circle').attr('class','circles1')
.attr('cx',function(d){return margin+xscale(d.date)})
.attr('cy',function(d){return height-yscale(d.vader)})
.style('fill','green')
.attr('r',3)
circles2=svg.append('g').selectAll('circle').data(sdata)
.enter().append('circle').attr('class','circles2')
.attr('cx',function(d){return margin+xscale(d.date)})
.attr('cy',function(d){return height-yscale(d.textblob)})
.style('fill','pink')
.attr('r',3)
d3.selectAll('.circles1')
.transition()
.duration(5000)
.attr('cy',function(d, i){
return height-yscale(sdata1[i].vader)
})
// d3.selectAll('circle#circles2')
// .transition()
// .attr('cy',function(d){return 0})
//tween 팩토리를 정의해야한다.
//주의사항, 리턴을 갖는 함수여야한다는 것.
//왜 꼭 return function(){}을 해야하나?
/*
function movey(d2){
let y1 = this.attr('cy')
let y2 = d2.vader
let interpolate=d3.interpolate(y1,y2);
interpolate;
} 하면 안되나??
*/
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>

How to do animation of sequential data with d3.js?

I have a sequential data. Data is an array divided into 30 steps.
In the first step I draw initial data. Then I take data from second step, compare it with data from previous step. And make some animation/transition.
Now I want to repeat animation for the rest of 28 steps.
If I will use code like this
var old_data = start_data;
for (var i = 0, i < rest_data.length; i++){
var new_data = rest_data[i];
var diff_data = diff(old_data, new_data);
var t0 = d3.transition().duration(3000);
var selection = d3.selectAll('g').data(diff_data)
selection.transition(t0).attr('my', function(d,i) { ... });
old_data = new_data;
}
it will not work because transition() is async code.The loop run faster than complete the first animation. And at best I will have an animation between data[0] and data[29].
What is the best way to create an animation with sequential data like my?
Use d3.transition().on('end', function() {...}), where function() { ... } some function with closure where I will store old_data, rest_data and other variables?
I don't like this solution because I have many variables to calculate diff_data, and I have to keep them in the closure.

You are correct: the for loop will run to the end almost instantly, and it will simply call that bunch of transitions at the same time, which, of course,
will not work.
There are some different solutions here. Good news is that transition().on("end"... is just one of them, you don't need to use it if you don't want.
My favourite one is creating a function that you call repeatedly with setTimeout or, even better, with d3.timeout.
This is the logic of it:
var counter = 0;//this is, of course, a counter
function loop(){
//if there is a data element for the next counter index, call 'loop' again:
if(data[counter + 1]){ d3.timeout(loop, delay)}
//access the data using the counter here,
//and manipulate the selection
//increase the counter
counter++;
}
Have a look at this demo:
var data = [30, 400, 170, 280, 460, 40, 250];
var svg = d3.select("body")
.append("svg")
.attr("width", 500)
.attr("height", 100);
var circle = svg.append("circle")
.attr("cy", 50)
.attr("cx", 250)
.attr("r", 10)
.attr("fill", "tan")
.attr("stroke", "black");
var counter = 0;
loop();
function loop() {
if (data[counter + 1]) {
d3.timeout(loop, 1000)
}
circle.transition()
.duration(500)
.attr("cx", data[counter]);
counter++
}
<script src="https://d3js.org/d3.v4.min.js"></script>

Updating several d3.js cartograms in the same container

I'm trying to update 4 cartograms in the same div.
First I create 4 original maps, each in its own svg, like this:
function makeMaps(data){
var mapsWrapper = d3.select('#maps');
data.forEach(function(topoJSON,i){
var quantize = d3.scale.quantize()
.domain([0, 1600000])
.range(d3.range(5).map(function(i) { return "q" + i; }));
var layer = Object.keys(topoJSON.objects)[0]
var svg = mapsWrapper.append('svg')
.attr("class","mapa")
.attr({
width: "350px",
height: "350px"
});
var muns = svg.append("g")
.attr("class", "muns")
.attr("id",layer)
.selectAll("path");
var geometry = topoJSON.objects[layer].geometries;
var carto = cartos[i]
var features = carto.features(topoJSON, geometry),
path = d3.geo.path()
.projection(projections[i]);
muns.data(features)
.enter()
.append("path")
.attr("class", function(d) {
return quantize(d.properties['POB1']);
})
.attr("d", path);
});
}
This part works well and creates 4 maps. After this, I want to update the paths in each map with the paths calculated by cartogram.js. The problem is that I can't get to the path data in each of the maps, here's what I'm trying to do:
...some code to calculate cartogram values
var cartograms = d3.selectAll(".mapa").selectAll("g").selectAll("path")
cartograms.forEach(function(region,i){
region.data(carto_features[i])
.select("title")
.text(function (d) {
return d.properties.nom_mun+ ': '+d.properties[year];
});
In cartograms I'm getting a nested selection: an array of paths for each map, which is what I though I needed, but inside the forEach I get the error region.data() is not a function. Each region is an array of paths each of which has a data property. I've tried with several ways of selecting the paths to no avail and I'm a little lost now. Thanks for your help

How do you create a d3 line function that will draw 2 lines for x, y1, y2 data?

I have an array of data in this format:
var data = [{x:0,y1:1, y2:2}, {x:1, y1:2, y2:2},...]
I'd like to use d3 to plot this with the help of the line function.
So, I created 2 paths on my svg container...
var path1 = svg.append("path");
var path2 = svg.append("path");
Now, to draw the first line, I have used:
var lineFunction = d3.svg.line()
.x(function(d){return d.x}
.y(function(d){return d.y1}
.interpolate("linear")
and
path1.attr("d", lineFunction(data))
And that worked great. However, how do I now draw the second line? I can of course create a new lineFunction that returns d.y2 for the y value, but that goes completely against the DRY principle. I think my workflow is not quite the right way to do it, so may I ask how are you actually supposed to do it? In other words, how should I create a line function that will work with both the y1 and y2 data?

To expand on the commend from #Lars, the trick here is to first pivot your data to be an array of objects that each represents an individual line.
var newData = [
{
name: "y1",
points: [ { x:0, y:1},{x:1,y:2}]
},
{
name: "y2",
points: [ { x:0, y:2},{x:1,y:2}]
},
];
Your lineFunction can then operate generically on x and y:
var lineFunction = d3.svg.line()
.x(function(d){return d.x}
.y(function(d){return d.y}
.interpolate("linear")
You can then bind this data to the elements in your visualisation and add a path for each data entry:
var lines = svg.selectAll(".line").data(newData);
lines.enter().append("path")
.attr("class","line")
.attr("d",function(d) {
return lineFunction(d.points);
});