如何在没有注释的情况下获得在dygraphs中显示的工具提示

我正在尝试使用 dygraphs 的 R 实现

提供的示例是

library(dygraphs)

dygraph(presidents, main = "Presidential Approval") %>%
dyAxis("y", valueRange = c(0, 100)) %>%
dyAnnotation("1950-7-1", text = "A", tooltip = "Korea") %>%
dyAnnotation("1965-1-1", text = "B",  tooltip = "Vietnam")

which results in the chart

将鼠标悬停在“A”上会生成带有“Korea”的工具提示

我渴望为每个点提供一个工具提示，最好完全免除文本要求 - 尽管将文本设置为具有最小高度/宽度值的“”可能就足够了。我还想以编程方式从包含日期和工具提示列的文件附加 dyAnnotations

df <- data.frame(date=as.Date(c("1950-7-1","1965-1-1")),tooltip=c("Korea","Vietnam"))

这是否可行？如果可行，如何实现？ TIA

Dygraphs 的大部分定制发生在CSS造型。例如，这是如何 https://gist.github.com/timelyportfolio/cf7b94048ffe7b6a0112我们可以更改默认的工具提示行为。考虑到这一点并得到一些帮助Dygraphs注释文档 http://dygraphs.com/annotations.html，我们可以对第一个问题做这样的事情。

# answers Stack Overflow question
#   http://stackoverflow.com/questions/27671576/how-can-i-get-tooltips-showing-in-dygraphs-without-annotation
# on how to customize annotations

library(dygraphs)

# question is two parts - let's handle part 1 first
dygraph(presidents, main = "Presidential Approval") %>%
  dyAxis("y", valueRange = c(0, 100))  %>%
  dyAnnotation("1950-7-1", text = "Korea", tooltip = ""
               # this is not necessary but think it better to be specific
               ,cssClass = "specialAnnotation") %>%
  # will leave this as before 
  dyAnnotation("1965-1-1", text = "Vietnam", tooltip = "") -> dyG

#this is a hack to set css directly
#  dyCSS designed to read a text css file
dyG$x$css = "
  /* if cssClass not assigned use .dygraphDefaultAnnotation */
  /*  !important is critical for the rules to be applied */
  .specialAnnotation {
    overflow: visible !important;
    width: initial !important;
  }
"

对于第二个问题，这是我们可以实现这一目标的一种方法

# now for part 2 
dyG = dygraph(presidents, main = "Presidential Approval") %>%
  dyAxis("y", valueRange = c(0, 100))

tooltips = list(
  list(x = "1950-7-1", tooltip = "", text = "Korea")
  ,list(x = "1965-1-1", tooltip = "", text = "Vietnam")
) 

annotator <- function(x,y){
  d = do.call(dyAnnotation,modifyList(list(dygraph=x),y))
  return(d)
}

dyG = Reduce( annotator, tooltips, init=dyG )

#this is a hack to set css directly
#  dyCSS designed to read a text css file
dyG$x$css = "
  /* if cssClass not assigned use .dygraphDefaultAnnotation */
  /*  !important is critical for the rules to be applied */
  .dygraphDefaultAnnotation {
    overflow: visible !important;
    width: initial !important;
    border: none !important;
    font-size: 200% !important;
  }
"

dyG