This function updates the color scheme of the legend and genes in a gene chart.
Arguments
- GC_chart
- The gene chart object to be modified. 
- colorScheme
- Optional; character or NULL, the name of a predefined color scheme to apply to the genes.Acceptable values include D3.js's built-in color schemes like "schemeCategory10", "schemeAccent", "schemeTableau10". 
- customColors
- Either NULL, a list of color values, or a named list of color values. 
Examples
genes_data <- data.frame(
  start = c(10, 50, 90, 130, 170, 210),
  end = c(40, 80, 120, 160, 200, 240),
  name = c('Gene 1', 'Gene 2', 'Gene 3', 'Gene 4', 'Gene 5', 'Gene 6'),
  group = c('A', 'A', 'B', 'B', 'A', 'C'),
  cluster = c(1, 1, 1, 2, 2, 2)
)
GC_chart(genes_data, cluster = "cluster", group = "group", height = "100px") %>%
  GC_color(colorScheme = "schemeCategory10")
GC_chart(genes_data, cluster = "cluster", group = "group", height = "100px") %>%
  GC_color(customColors = c("red", "orange", "green"))
GC_chart(genes_data, cluster = "cluster", group = "group", height = "100px") %>%
  GC_color(customColors = list(A = "yellow", B = "pink", C =  "purple"))
