How to use d3.scaleLinear to find the radius of a map in d3 - d3.js

Question

I have a chart as shown below
where the radius of the pie chart on the chart is am trying to do it as shown below
<PieChartMarkers
totalSites={totalSites}
key={i}
keymarket={name}
pieData={pieData}
x={projection(coordinates)[0]}
y={projection(coordinates)[1]}
**radius={this.getMarketRadius(totalCase)}**
mouseOverHandler={this.showTooltip}
mouseOutHandler={this.hideTooltip}
/>
getMarketRadius = (totalCase) => {
let radius = null;
// let data=d3.scaleLinear([10,130]).range([0,960]);
let callback= d3.scaleLinear()
.range([0, totalCase])
.domain([10, 130])
radius = totalCase / 650 + 10;
console.log(radius)
return radius;
};
currently i am getting the radius radius = totalCase / 650 + 10; which is working fine but suggestion is to use d3.scaleLinear to get the radius of the on chart when trying to use i am getting the value as 1313316 using the below code snippet
//totalCase is the variable value coming from API
let callback= d3.scaleLinear()
.range([0, totalCase])
.domain([10, 130]
please help me understand how to get the radius using d3.scaleLinear to draw the pie chart on the map

Answer 1

First of all, you should not use a linear scale to get these radii: we encode the data as the area of the circles, not as their radii. That said, you should use d3.scaleSqrt. Also, set the 0 range for the 0 domain, because there should be no circle if there are no cases.
So, your function would be something like this:
getMarketRadius = totalCase => {
return d3.scaleLinear().range([0, totalCase]).domain([0, 130])(totalCase);
};
A better option is just setting the scale outside the function, and using it directly for setting the radius.
myScale = d3.scaleLinear()
.range([0, totalCase])
.domain([0, 130]);
radius={this.myScale(totalCase)}