I am trying to create a pulse effect on a circle by increasing and decreasing its radius. I would like the circle to grow and shrink based on a given data set. I can only get the transition function to ether increase or decrease the radius but not both.
d3 automatically creates a different circle for each value in the array. How can I make it so that one circle's radius grows and shrinks as it iterates through the array? a simple version of what I have so far is below. Thanks for any help you can offer.
dataset = [30, 80, 150, 90, 20, 200, 180]
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
var circle = svg.selectAll("circle")
.data(dataset)
.enter()
.append("circle");
circle
.attr("cx", 500)
.attr("cy", h/2)
.attr("r", dataset[0])
.attr("fill", "orange");
This doesn't really fit with the general D3 data/enter/update/exit pattern because you're not controlling multiple DOM elements, but changing attributes of a single one. You can however do this quite easily with a loop that adds the transitions as specified. The code would look like this.
dataset.forEach(function(d, i) {
circle.transition().duration(duration).delay(i * duration)
.attr("r", d);
});
For a complete example, see here.
Another option that creates a continuously pulsing circle:
http://bl.ocks.org/chiester/11267307
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