Difference Chart
This example shows a difference chart comparing daily temperatures in New York and San Francisco, with the gap between the two lines shaded green when New York is warmer and red when San Francisco is warmer. The visualization uses D3 v4’s `d3.area`, `d3.line`, and `d3.scaleTime` to render the SVG paths, while `clipPath` elements with `area.y0` values clip the colored regions based on which city has the higher temperature. The data is loaded from a TSV file containing date and temperature values for both cities.