How to change the color of marker-points dynamically based on y-position

Question

I have below interactive plot using highchart js library in R

library(highcharter)
hchart(data.frame(\'Date\' = seq(Sys.Da         


        

Answer 1

The is no such option in the API. You need to write some custom code. The simplest way is to use chart.events.load event, loop through all points of your series, find the ones in the red or green zone and update their marker options separately. To write a JavaScript code in R, you can use JS("") function.

Here is the whole sample code:

library(highcharter)
hchart(data.frame('Date' = seq(Sys.Date(), Sys.Date() - 10, by = '-1 day'), 'Value' = sample(c(-1, 1), 11, replace = T), 'variable' = 'aa') %>%
         mutate(color = ifelse(Value < 0, "#41c83b", "#E0245E")), 
       "line", 
       zIndex = 1, opacity = 0.9,
       hcaes(x = Date, y = Value, group = variable),
       zones = list(list(value = 0, color = hex_to_rgba("#41c83b", 1)), list(color = hex_to_rgba("#E0245E", 1))),
       marker = list(fillColor = "#fff", radius = 5, lineWidth = 2)) %>%
  hc_chart(events = list(load = JS("function () {
    this.series[0].points.forEach(function (point) {
      if (point.y > 0) {
        point.update({
          marker: {
            lineColor: 'red'
          }
        }, false);
      } else {
        point.update({
          marker: {
            lineColor: 'green'
          }
        }, false);
      }
    });
    this.redraw();
  }")))

API Reference: https://api.highcharts.com/highcharts/chart.events.load https://api.highcharts.com/class-reference/Highcharts.Chart#update https://api.highcharts.com/class-reference/Highcharts.Point#update