even if all the values are right before it reaches to the drawing part,
the code below keeps returrning error message

Expected number, "MNaN,NaNLNaN,NaNL…".

my lineRadial function is as below.

```
var radarLine = d3.lineRadial()
        .radius(function(d) {

            return rscale(d.value)
        })
        .angle(function(i) { return i * angleSlice })

```

And i called this function to draw radial chart like below.

```
var blobWrapper = g.selectAll(".radarWrapper")
        .data(data)
        .join('g')
        .attr("class", "radarWrapper")

blobWrapper.append('path')
            .attr('class', 'radarArea')
            .attr('d', function(d) { return radarLine(d); })
            .style('fill', function(d, i) { return cfg.color[i] })
            .style('fill-opacity', cfg.opacityArea)

```

I fixed this error by putting one dummy parameter in the line function.

```
var radarLine = d3.radialLine()
    .radius(function(d) {
        return rscale(d.value)
    })
    .angle(function(d, i) { return i * angleSlice })

```

just by adding 'd' parameter to the angle function, it started working.
why is it?