How Can I Use Symbols With a Legend - d3.js

Question

I've got a legend, with colored rectangles...
I'd like to replace the rectangles with symbols (i.e., circle, cross, diamond, square). I can't figure out how to do that.
I've been using variations of .attr("d", d3.svg.symbol().type('circle'). For instance, I tried:
legendRect
.attr("d", d3.svg.symbol().type(function (d) { return d[2] })
and I tried:
legendRect.append("svg:path")
.attr("d", d3.svg.symbol().type((d: any) => { return d[2] }))
d[2] is "supposed to be" pulling from legendData, as shown in the below code example...like it does with d[1] for the fill.
But I don't ever see anything change.
Here's the code I'm using for the legend, without the symbol stuff, below. What am I doing wrong and how can I change the rectangles to symbols? Where do I need to add what?
var legendData = [["OA", "yellow", "circle"], ["OI", "blue", "cross"], ["RARC", "green", "diamond"], ["CAPE", "red", "square"], ["Other", "black", "triangleDown"]];
var legend = this.svg.append("g")
.attr("class", "legend")
.attr("height", 0)
.attr("width", 0)
.attr('transform', 'translate(-20,250)');
var legendRect = legend.selectAll('rect').data(legendData);
legendRect.enter()
.append("rect")
.attr("x", width - 65)
.attr("width", 10)
.attr("height", 10)
;
legendRect
.attr("y", function (d, i) {
return i * 20;
})
.style("fill", function (d) {
return d[1];
})
var legendText = legend.selectAll('text').data(legendData);
legendText.enter()
.append("text")
.attr("x", width - 52);
legendText
.attr("y", function (d, i) {
return i * 20 + 9;
})
.text(function (d) {
return d[0];
});

Answer 1

Here's how I would code it. Notice, that I data-bind to a wrapper g element and then place the symbol and text into it for each legend item. You can then position the g instead of positioning the text and "symbol" separately. This also removes the need for double-binding the data.
var legendData = [["OA", "yellow", "circle"], ["OI", "blue", "cross"], ["RARC", "green", "diamond"], ["CAPE", "red", "square"], ["Other", "black", "triangleDown"]];
var svg = d3.select('body').append('svg').attr('width', 500).attr('height', 500);
var legend = svg.append('g')
.attr("class", "legend")
.attr("height", 0)
.attr("width", 0)
.attr('transform', 'translate(20,20)');
var legendRect = legend
.selectAll('g')
.data(legendData);
var legendRectE = legendRect.enter()
.append("g")
.attr("transform", function(d,i){
return 'translate(0, ' + (i * 20) + ')';
});
legendRectE
.append('path')
.attr("d", d3.svg.symbol().type((d) => { return d[2] }))
.style("fill", function (d) {
return d[1];
});
legendRectE
.append("text")
.attr("x", 10)
.attr("y", 5)
.text(function (d) {
return d[0];
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

Answer 2

This is a implementation which uses symbols for your legend. You can use the symbols like the following:
svg.selectAll('.symbol')
.data(legendData)
.enter()
.append('path')
.attr('transform', function(d, i) {
return 'translate(' + (20) + ',' + ((i * 20) + 10) + ')';
})
.attr('d', d3.symbol().type(function(d, i) {
if (d[2] === "circle") {
return d3.symbolCircle;
} else if (d[2] === "cross") {
return d3.symbolCross;
} else if (d[2] === "diamond") {
return d3.symbolDiamond;
} else if (d[2] === "square") {
return d3.symbolSquare;
} else {
return d3.symbolTriangle;
}
})
.size(100))
.style("fill", function(d) {
return d[1];
});
Then you can set your legend labels like the following:
svg.selectAll('.label')
.data(legendData)
.enter()
.append('text')
.attr("x", "40")
.attr("y", function(d, i){ return ((i * 20)+15);})
.text(function(d) {
return d[0];
});
Check fiddle here - https://jsfiddle.net/zoxckLe3/
P.S. - Above solution uses d3 v4. To achieve the same in v3, use the following line .attr('d', d3.svg.symbol().type(function(d){return d[2];})) instead of the part where I match d[2] to the symbol name.

Answer 3

For adding image icons, you can use below code.
legend.append("**image**")
.attr("x", 890)
.attr("y", 70)
.attr("width", 20)
.attr("height", 18)
.attr("xlink:href",function (d) {
**return "../assets/images/dev/"+d+".png";**
})
This works for me..