data that contains objects each with
positivityRate keys, you can create a line chart with code like this:
tickFormat option used in the y scale above is powerful. You can pass it a function or you can use a ‘format specifier’. Plot includes a handful of formatting functions,
Plot.formatMonth, or you can use your own (receive a value, return a formatted string).
A format specifier is a string that describe how you want Plot to format your labels. Plot supports the specifiers from
d3-format, for formatting numbers, or
d3-time-format, for formatting dates and times. The string used above,
".0%", says ‘round to the nearest integer, multiply by 100, and add a percent sign suffix’. Thus
12%. Another useful specifier is
~s, which trims insignificant trailing zeros — the number
1500 would be formatted as
1.5k. The format specifiers available from
d3-time-format are less directly useful, if only because Plot uses them internally to label date and time axes automatically.