# This is just c(red, grey, green)
my_colour_pal <- c("#bc0303", "#4b5566", "#17a008")
df <-
  data.frame(Group1 = c("one", "one", "two"),
             Group2 = c("val1", "val2", "val3"),
             Value = c(10, 10, 10),
             Colour = c(-1, 0, 1), stringsAsFactors = FALSE)

treemap(df, index = c("Group1", "Group2"), type = "value",
        vSize = "Value", vColor = "Colour", palette = my_colour_pal)

df <-
  data.frame(Group1 = c("one", "one", "two"),
             Group2 = c("val1", "val2", "val3"),
             Value = c(10, 0, 10),
             Colour = c(-1, 0, 1), stringsAsFactors = FALSE)

treemap(df, index = c("Group1", "Group2"), type = "value",
        vSize = "Value", vColor = "Colour", palette = my_colour_pal)

df <-
  data.frame(Group1 = c("one", "one", "two"),
             Group2 = c("val1", "val2", "val3"),
             Value = c(0, 0, 10),
             Colour = c(-1, 0, 1), stringsAsFactors = FALSE)

treemap(df, index = c("Group1", "Group2"), type = "value",
        vSize = "Value", vColor = "Colour", palette = my_colour_pal)

Error in do.call("format", args.legend) : second argument must be a list

my_colour_pal <- c("#bc0303", "#4b5566", "#17a008")
df <-
  data.frame(Group1 = c("one", "one", "two"),
             Group2 = c("val1", "val2", "val3"),
             Value = c(10, 10, 0),
             Colour = c(-1, 0, 1), stringsAsFactors = FALSE)

treemap(df, index = c("Group1", "Group2"), type = "value",
        vSize = "Value", vColor = "Colour", palette = my_colour_pal)

df <-
  data.frame(Group1 = c("one", "one", "two"),
             Group2 = c("val1", "val2", "val3"),
             Value = c(10, 10, 0),
             Colour = c(-1, -1, 1), stringsAsFactors = FALSE)

treemap(df, index = c("Group1", "Group2"), type = "value",
        vSize = "Value", vColor = "Colour", palette = my_colour_pal)

Error in do.call("format", args.legend) : second argument must be a list