leaflet高级交互特性怎么用

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在制作高质量在线数据地图的项目中，leaflet结合扩展的HTML性能，可以呈现非常人性化的动态效果，如能结合css、shiny等装饰器和交互框架，几乎可以胜任常见的动态交互网站的制作。

library("sp")

library("leaflet")

options(stringsAsFactors = FALSE,check.names = FALSE)

锁定目录：

setwd("D:/R/mapdata/State")

导入美国地图素材（含数据）

states<-geojsonio::geojson_read("us-states.geojson", what = "sp")

一个简单的开始：（引用mapbox地图）

m <- leaflet(states) %>%

  setView(-96, 37.8, 4) %>%  #设置呈现的视觉中心

  addProviderTiles("MapBox", options = providerTileOptions(

    id = "mapbox.light",       #添加地图图层

    accessToken = Sys.getenv('MAPBOX_ACCESS_TOKEN')))

m %>% addPolygons()   #地图呈现

#分箱及设置色盘：

bins <- c(0, 10, 20, 50, 100, 200, 500, 1000, Inf)

pal <- colorBin("YlOrRd", domain = states$density, bins = bins)

m %>% addPolygons(

  fillColor = ~pal(density),   #显式声明颜色映射变量

  weight = 2,                       #线宽

  opacity = 1,                     #透明度

  color = "white",               #颜色

  dashArray = "3",

  fillOpacity = 0.7)             #填充透明度

m %>% addPolygons(

  fillColor = ~pal(density),

  weight = 2,

  opacity = 1,

  color = "white",

  dashArray = "3",

  fillOpacity = 0.7,

  highlight = highlightOptions(     #设置高亮属性

    weight = 5,

    color = "#666",

    dashArray = "",

    fillOpacity = 0.7,

    bringToFront = TRUE))

#设置鼠标点击事件：

labels <- sprintf("<strong>%s</strong><br/>%g people / mi²",states$name,states$density) %>% lapply(htmltools::HTML)  #转化为HTML格式标签

m <-m %>% addPolygons(

  fillColor = ~pal(density),

  weight = 2,

  opacity = 1,

  color = "white",

  dashArray = "3",

  fillOpacity = 0.7,

  highlight = highlightOptions(

    weight = 5,

    color = "#666",

    dashArray = "",

    fillOpacity = 0.7,

    bringToFront = TRUE

    ),

    label = labels,

    labelOptions = labelOptions(    #标签选项设置（参数类别HTML属性）

    style=list("font-weight"="normal",padding="3px 8px"),

    textsize="15px",

    direction="auto")

  );m

#增加图例：

m %>% addLegend(pal = pal, values = ~density, opacity = 0.7, title = NULL,

  position = "bottomright")

以下是该案例的完整代码：

# From http://leafletjs.com/examples/choropleth/us-states.js

（数据源，js格式记得保存为geojson格式）

bins <- c(0, 10, 20, 50, 100, 200, 500, 1000, Inf)

pal <- colorBin("YlOrRd", domain = states$density, bins = bins)

labels <- sprintf(

  "<strong>%s</strong><br/>%g people / mi²",

  states$name, states$density

) %>% lapply(htmltools::HTML)

leaflet(states) %>%

  setView(-96, 37.8, 4) %>%

  addProviderTiles("MapBox", options = providerTileOptions(

    id = "mapbox.light",

    accessToken = Sys.getenv('MAPBOX_ACCESS_TOKEN'))) %>%

  addPolygons(

    fillColor = ~pal(density),

    weight = 2,

    opacity = 1,

    color = "white",

    dashArray = "3",

    fillOpacity = 0.7,

    highlight = highlightOptions(

      weight = 5,

      color = "#666",

      dashArray = "",

      fillOpacity = 0.7,

      bringToFront = TRUE),

    label = labels,

    labelOptions = labelOptions(

      style = list("font-weight" = "normal", padding = "3px 8px"),

      textsize = "15px",

      direction = "auto")) %>%

  addLegend(pal = pal, values = ~density, opacity = 0.7, title = NULL,

    position = "bottomright")

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