Setting axis range?

[Hvass-Labs]

Two related questions:

1. I am making a simple line-plot with dates on the x-axis and values on the y-axis. The values range between e.g. 20 and 40, so Plot adapts the y-axis to that range, but I want the y-axis to begin already at zero. How do I manually set the y-axis range e.g. to start at zero?

2. Sometimes the data contains negative values as well e.g. down to -30. In this case I want to keep the plot's default range for the y-axis and not set it to start at zero. But I want to use the exact same code to generate the plot, because my data comes from a database. How do I change the y-axis range to e.g. the minimum of its default range and some other value such as zero?

Thanks!

[Fil]

1. use the y: {zero: true} option, or add a mark that includes 0 as a value for y (typically, Plot.ruleY([0])).
2. same answer :)

[Hvass-Labs]

y: {zero: true} is an elegant solution that works in my case where I want to ensure zero is on the y-axis. But for an arbitrary value a you suggest using Plot.ruleY([a]), which adds a horizontal line that I don't want. How can I avoid that? Thanks.

[Fil]

Plot.ruleY([a], {filter: false})? It will add a to the domain, but won't display anything.
See also #1577

[Hvass-Labs]

OK, thanks. It's hacky but it works :-)