使用 gridSVG 和 ggplot2 v.0.9.0 进行交互式点标签

我想以交互方式在 ggplot 中标记点，以便将鼠标悬停在点上会显示标签。

我正在尝试调整给出的答案这个问题 https://stackoverflow.com/questions/8972642/how-do-you-relate-ggplot2-grobs-back-to-the-data这样它就可以在最新版本的 ggplot2 中运行。受到 ggplot google group 评论的影响，here https://groups.google.com/forum/?fromgroups#!topic/ggplot2/PujkP1QvvCM，我使用了最新版本的geom-point-.r作为模板，在各个地方的gp参数中添加了“标签”字段。然后我从 kohske 的答案中复制了剩余的代码。但它不起作用——生成的 svg 中没有任何标签，我不明白为什么。

我确实注意到了point_grobs_labels为空，当我查看时grid.get(point_grob_names[1])$gp，没有标签字段...

library(ggplot2)
library(gridSVG)
library(proto)
library(rjson)

geom_point2 <- function (mapping = NULL, data = NULL, stat = "identity", 
                         position = "identity",
                         na.rm = FALSE, ...) {
  ggplot2:::GeomPoint$new(mapping = mapping, data = data, stat = stat, 
                          position = position, 
                          na.rm = na.rm, ...)
}

GeomPoint2 <- proto(ggplot2:::Geom, {
  objname <- "point"

  draw_groups <- function(., ...) .$draw(...)
  draw <- function(., data, scales, coordinates, na.rm = FALSE, ...) {    
    data <- remove_missing(data, na.rm, 
                           c("x", "y", "size", "shape"), name = "geom_point")
    if (empty(data)) return(zeroGrob())

    with(coord_transform(coordinates, data, scales), 
         ggname(.$my_name(), pointsGrob(x, y, size=unit(size, "mm"), pch=shape, 
                                        gp=gpar(
                                          col=alpha(colour, alpha),
                                          fill = alpha(fill, alpha),  
                                          label = label, 
                                          fontsize = size * .pt)))
    )
  }

  draw_legend <- function(., data, ...) {
    data <- aesdefaults(data, .$default_aes(), list(...))

    with(data,
         pointsGrob(0.5, 0.5, size=unit(size, "mm"), pch=shape, 
                    gp=gpar(
                      col = alpha(colour, alpha), 
                      fill = alpha(fill, alpha), 
                      label = label,
                      fontsize = size * .pt)
         )
    )
  }

  default_stat <- function(.) StatIdentity
  required_aes <- c("x", "y")
  default_aes <- function(.) aes(shape=16, colour="black", size=2, 
                                 fill = NA, alpha = NA, label = NA)

})

p <- ggplot(mtcars, aes(mpg, wt, label = rownames(mtcars))) + geom_point2() + facet_wrap(~ gear)
print(p)

grob_names <- grid.ls(print = FALSE)$name
point_grob_names <- sort(grob_names[grepl("point", grob_names)])
point_grobs_labels <- lapply(point_grob_names, function(x) grid.get(x)$gp$label)  

jlabel <- toJSON(point_grobs_labels)

grid.text("value", 0.05, 0.05, just = c(0, 0), name = "text_place", gp = gpar(col = "red"))

script <- '
var txt = null;
function f() {
var id = this.id.match(/geom_point2.([0-9]+)\\.points.*\\.([0-9]+)$/);
txt.textContent = label[id[1]-1][id[2]-1];
}

window.addEventListener("load",function(){
var es = document.getElementsByTagName("circle");
for (i=0; i<es.length; ++i) es[i].addEventListener("mouseover", f, false);

txt = (document.getElementById("text_place").getElementsByTagName("tspan"))[0];

},false);
'

grid.script(script = script)
grid.script(script = paste("var label = ", jlabel))

gridToSVG()

尝试这个：

library(ggplot2)
library(gridSVG)
library(proto)
library(rjson)
mtcars2 <- data.frame(mtcars, names = rownames(mtcars))

geom_point2 <- function (...) {
  GeomPoint2$new(...)
}

GeomPoint2 <- proto(ggplot2:::Geom, {
  objname <- "point"

  draw_groups <- function(., ...) .$draw(...)
  draw <- function(., data, scales, coordinates, na.rm = FALSE, ...) {    
    data <- remove_missing(data, na.rm, 
                           c("x", "y", "size", "shape"), name = "geom_point")
    if (empty(data)) return(zeroGrob())
    name <- paste(.$my_name(), data$PANEL[1], sep = ".")
    with(coord_transform(coordinates, data, scales), 
         ggname(name, pointsGrob(x, y, size=unit(size, "mm"), pch=shape, 
                                        gp=gpar(
                                          col=alpha(colour, alpha),
                                          fill = alpha(fill, alpha),  
                                          label = label, 
                                          fontsize = size * .pt)))
    )
  }

  draw_legend <- function(., data, ...) {
    data <- aesdefaults(data, .$default_aes(), list(...))

    with(data,
         pointsGrob(0.5, 0.5, size=unit(size, "mm"), pch=shape, 
                    gp=gpar(
                      col = alpha(colour, alpha), 
                      fill = alpha(fill, alpha), 
                      label = label,
                      fontsize = size * .pt)
         )
    )
  }

  default_stat <- function(.) StatIdentity
  required_aes <- c("x", "y")
  default_aes <- function(.) aes(shape=16, colour="black", size=2, 
                                 fill = NA, alpha = NA, label = NA)

})

p <- ggplot(mtcars2, aes(mpg, wt, label = names)) + geom_point2() +facet_wrap(~ gear)
print(p)

grob_names <- grid.ls(print = FALSE)$name
point_grob_names <- sort(grob_names[grepl("point", grob_names)])
point_grobs_labels <- lapply(point_grob_names, function(x) grid.get(x)$gp$label)

jlabel <- toJSON(point_grobs_labels)

grid.text("value", 0.05, 0.05, just = c(0, 0), name = "text_place", gp = gpar(col = "red"))

script <- '
var txt = null;
function f() {
    var id = this.id.match(/geom_point.([0-9]+)\\.points.*\\.([0-9]+)$/);
    txt.textContent = label[id[1]-1][id[2]-1];
}

window.addEventListener("load",function(){
    var es = document.getElementsByTagName("circle");
    for (i=0; i<es.length; ++i) es[i].addEventListener("mouseover", f, false);

    txt = (document.getElementById("text_place").getElementsByTagName("tspan"))[0];

},false);
'
grid.script(script = paste("var label = ", jlabel))
grid.script(script = script)

gridToSVG()

没有什么大的变化，但我必须添加

mtcars2 <- data.frame(mtcars, names = rownames(mtcars))

and then

p <- ggplot(mtcars, aes(mpg, wt, label = rownames(mtcars)))
     + geom_point2() + facet_wrap(~ gear)

也更改为

p <- ggplot(mtcars2, aes(mpg, wt, label = names)) 
     + geom_point2() +facet_wrap(~ gear)

因为我们有rownames(mtcars)

rownames(mtcars)
 [1] "Mazda RX4"           "Mazda RX4 Wag"       "Datsun 710"          "Hornet 4 Drive"     
 [5] "Hornet Sportabout"   "Valiant"             "Duster 360"          "Merc 240D"          
 [9] "Merc 230"            "Merc 280"            "Merc 280C"           "Merc 450SE"
.....

然后标签（我们设法通过其他修改获得）保持不变，即不重新排列gears，仅除以它：

point_grobs_labels
[[1]]
 [1] "Mazda RX4"          "Mazda RX4 Wag"      "Datsun 710"         "Hornet 4 Drive"    
 [5] "Hornet Sportabout"  "Valiant"            "Duster 360"         "Merc 240D"         
 [9] "Merc 230"           "Merc 280"           "Merc 280C"          "Merc 450SE"        
[13] "Merc 450SL"         "Merc 450SLC"        "Cadillac Fleetwood"
[[2]]
....

但将这些标签名称作为一列可以解决问题。

point_grobs_labels 
[[1]]
 [1] "Hornet 4 Drive"      "Hornet Sportabout"   "Valiant"             "Duster 360"         
 [5] "Merc 450SE"          "Merc 450SL"          "Merc 450SLC"         "Cadillac Fleetwood" 
 [9] "Lincoln Continental" "Chrysler Imperial"   "Toyota Corona"       "Dodge Challenger"   
[13] "AMC Javelin"         "Camaro Z28"          "Pontiac Firebird"   

[[2]]
....