{"version":"1.0","type":"rich","title":"Melting Data for Multiple Lines","description":"This example shows population over time by region as multiple smoothed lines, using a color legend to distinguish regions. The data is melted from wide to long format in `loadAndProcessData`, combining UN population estimates (1950–2014) with medium-variant projections (2015–2100). D3 v5 APIs include `d3.nest`, `d3.line` with `curveBasis`, `d3.scaleTime`, `d3.scaleLinear`, and `d3.scaleOrdinal`. A custom `colorLegend` function renders SVG legends, while axes use `d3.axisBottom` and `d3.axisLeft` with tick formatting via `d3.format`.","provider_name":"VizHub AI Studio","provider_url":"https://vizhub.com","html":"<iframe src=\"https://vizhub.com/viz/cf2c9a4fe0d74c57a97137a515f30504?mode=embed\" width=\"960\" height=\"500\" scrolling=\"no\" frameborder=\"0\"></iframe>","width":960,"height":500,"cache_age":3600}