用圆圈传单 R 创建图例 [英] Creating legend with circles leaflet R

问题描述

我正在尝试创建一个带有变量大小的点的传单地图.是否可以创建一个具有代表不同变量值的不同大小圆圈的图例?我发现另一篇文章展示了如何将图例中的正方形转换为圆形，但不确定如何更改图例中不同圆圈的大小.

I'm trying to create a leaflet map with points sized by a variable. Is it possible to create a legend with different sized circles representing the different variable values? I found another post showing how to convert squares to circles in the legend, but am not sure how to change the size of different circles in the legend.

例如，这是一个虚拟脚本，它创建与变量的 2 类(5 和 10)相关联的 10 个点.我想要一个图例，其中两个圆的大小与 addCircleMarkers 指定的大小相同，半径为 5 和 10.如果有人可以修改以创建我想要的东西，我将不胜感激！谢谢！

For example, here's a dummy script which creates 10 points associated with 2 classes of a variable (5 and 10). I'd like a legend with two circles the same size as that specified with addCircleMarkers with a radius of 5 and 10. If anyone can modify to create what I want I would be extremely grateful! Thanks!

library(shiny)
library(leaflet)

#create data
Points<-data.frame(x=runif(10,20,21), y=runif(10,0,1), var=rep(c(5,10),5))
map = leaflet() %>% addTiles()

# Set up shiny app
shinyApp(ui=bootstrapPage(
tags$style(type = "text/css", "html, body {width:100%;height:100%}",
".leaflet .legend i{
border-radius: 50%;
width: 10px;
height: 10px;
margin-top: 4px;
}
"
),
leafletOutput("myMap", width = "100%", height = "100%")),

server= function(input, output){

output$myMap = renderLeaflet({map %>% 
    addCircleMarkers(Points$x,Points$y,radius=Points$var) %>%
    addLegend(colors=rep("blue",2), labels=c(5,10))
  })
})

推荐答案

你很幸运.仔细查看 leaflet.js 会发现，您在 addLegend 命令中添加的配置实际上是用于创建图例项:

You're in luck. A closer look at the leaflet.js shows that the configurations your add inside the addLegend command, are used literally to create the legend items:

leaflet.js 的第 1083 - 1086 行:

Lines 1083 - 1086 from leaflet.js:

for (var i = 0; i < colors.length; i++) {
  legendHTML += '<i style="background:' + colors[i] + ';opacity:' +
                options.opacity + '"></i> ' + labels[i] + '<br/>';
}

这样，我们可以潜入一些额外的样式.在 colors 论证中，我们添加了一些 width 和 height 来改变 i 标签的大小(=传说圈).并且(这是可选的)我们可以使 labels 成为具有修改对齐样式的 div ，因为如果圆圈得到，它们往往会卡在行的顶部大.

This way, we can sneak in some extra styling. Within the colors arguement, we add some width and height to change the size of the i tag (= the legend circle). And (this is optional) we can make the labels a div with modified alignment style, because they tend to be stuck way to the top of the line, if the circle gets big.

我冒昧地为您创建了一个自定义图例函数.这需要一个额外的圆圈大小值.(对于这个应用程序来说，这是一个非常小的功能.)然后它添加了我上面提到的样式，而您无需担心拼写错误或其他错误.请注意，标准尺寸为 10.

I took the liberty to create a custom legend function for you. This takes an additional value for the circle sizes. (It's a very minimal function for just this one application.) It then adds the styling I mentioned above without you needing to worry about typos or other errors. Note that the standard size is 10.

代码如下.玩得开心！如果有任何错误或错误，请写出来.我无法测试所有可能的情况.

Code below. Have fun! And please write if there are any mistakes or bugs. I could not test for every possible scenario.

library(shiny)
library(leaflet)

#create data
Points<-data.frame(x=runif(10,20,21), y=runif(10,0,1), var=rep(c(5,10),5))
map = leaflet() %>% addTiles()

# Set up shiny app
shinyApp(
  ui = bootstrapPage(
    tags$style(type = "text/css", "html, body {width:100%;height:100%}",
      ".leaflet .legend i{
      border-radius: 50%;
      width: 10px;
      height: 10px;
      margin-top: 4px;
      }
    "),
    leafletOutput("myMap", width = "100%", height = "100%")
  ),

  server = function(input, output){
    addLegendCustom <- function(map, colors, labels, sizes, opacity = 0.5){
      colorAdditions <- paste0(colors, "; width:", sizes, "px; height:", sizes, "px")
      labelAdditions <- paste0("<div style='display: inline-block;height: ", sizes, "px;margin-top: 4px;line-height: ", sizes, "px;'>", labels, "</div>")
    
      return(addLegend(map, colors = colorAdditions, labels = labelAdditions, opacity = opacity))
    }
    
    output$myMap = renderLeaflet({map %>% 
      addCircleMarkers(Points$x,Points$y,radius=Points$var) %>%
      addLegendCustom(colors = c("blue", "blue", "red"), labels = c("A", "B", "C"), sizes = c(10, 20, 40))
    })
  }
)

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