R plotly customdata 格式变化

我试图通过javascrit访问分配给每个数据点的customdata(例如， for each 点分配一个超链接).然而，我注意到数据格式从一个图变为另一个图，这似乎很奇怪.

在本例中(基于this篇文章)，这非常有效，即fill美学是character向量:

library(plotly)
library(htmlwidgets)

js <- "function(el, x) {
         el.on('plotly_click', function(d) {
           console.log(d);
           console.log(d.points[0].data.customdata[0]);
       });
       }"

X <- data.frame(x = c(1, 2, 1, 2), y = c(1, 1, 2, 2), z = as.character(1:4), mydata = letters[1:4])

gg <- ggplot(X, aes(x = x, y = y, customdata = mydata)) + geom_tile(aes(fill = z))

ggplotly(gg) %>% onRender(js)

As can be seen, a single and correct custom data shows up when clicking on each point. The structure of the customdata is similar to other plots.

然而，当输入z作为数字变量时，customdata的 struct 表现得很奇怪:

X <- data.frame(x = c(1, 2, 1, 2), y = c(1, 1, 2, 2), z = 1:4, mydata = letters[1:4])

gg <- ggplot(X, aes(x = x, y = y, customdata = mydata)) + geom_tile(aes(fill = z))

ggplotly(gg) %>% onRender(js)

Is this a bug? How can I fix this? In fact, my dataset is much larger than the one in this example.