✅ – Nesho – 10-41 Feb 25

Hello, I'm using d3 to render charts. I have a problem with generating an area with d3.area, the area is being generated outside of my svg size, even though I'm giving the y-scale the same size as my svg. Any ideas?

export function useD3Scales<T>({ data, xKey, yKey }: Options<T>) {
  const { width, height, margin } = useResponsiveContainerSize();

  const xScale = d3
    .scaleTime()
    .domain(
      d3.extent(data, (d, i) => {
        return xKey ? xKey(d) : i;
      })
    )
    .range([margin.left, width - margin.right]);

  const yScale = d3
    .scaleLinear()
    .domain(d3.extent(data, (d) => d[yKey]))
    .range([height - margin.bottom, margin.top]);

  return { xScale, yScale };
}

The area component

export function Area<T>({
  color = 'blue',
  data,
  dataKey,
  line = true,
  ...rest
}: AreaProps<T>) {
  const { xScale, yScale } = useD3Scales({
    data,
    yKey: dataKey,
  });
  const { theme } = useTheme();

  console.log(yScale.range());

  const areaGenerator = useMemo(() => {
    return d3
      .area<T>()
      .x((_, i) => xScale(i))
      .y0(yScale(0))
      .y1((d) => yScale(d[dataKey]));
  }, [yScale, xScale]);

  const area = useMemo(() => areaGenerator(data), [areaGenerator]);
  const colorScheme = theme.colors[color][5];

  return (
    <>
      {line && <Line data={data} dataKey={dataKey} color={color} />}
      <path {...rest} fill={colorScheme} fillOpacity={0.1} d={area} />
    </>
  );
}

Result, as you can see, the height of the area is 8781, when it should be 226 (the height of the svg)

The line above, using the same scales

Logging the range gives me [226, 0], which is correct.

Solved it. The issue was that I was doing .domain(d3.extent(data, (d) => d[yKey])) in the yScale, when I needed to give it a minimum value of 0 ,and just find the max value .domain([0, d3.max(data, (d) => d[yKey])]).
The area calculates and plots correctly now.