想要在传单地图中添加 10 种不同类型的图标

Question

看看我的 R 代码，在这里我可以标记两种不同类型的标记图标，但我想用 10 种不同类型的标记图标标记 quakes$mag 列的所有 10 个值。

 quakes1 <- quakes[1:10,]

leafIcons <- icons(
  iconUrl = ifelse(quakes1$mag < 4.6,
                   "http://leafletjs.com/examples/custom-icons/leaf-green.png",
                   "http://leafletjs.com/examples/custom-icons/leaf-red.png"
  ),
  iconWidth = 38, iconHeight = 95,
  iconAnchorX = 22, iconAnchorY = 94,
  shadowUrl = "http://leafletjs.com/examples/custom-icons/leaf-shadow.png",
  shadowWidth = 50, shadowHeight = 64,
  shadowAnchorX = 4, shadowAnchorY = 62
)

leaflet(data = quakes1) %>% addTiles() %>%
  addMarkers(~long, ~lat, icon = leafIcons)

我尝试使用 switch 语句而不是 ifelse，但它不适用于 switch。

Answer 1

您的ifelse 是一个矢量化函数，它为leafIcons 创建了您的图标矢量。有多种方法可以矢量化 switch 或基于矢量创建 leafIcons 的替代方法 - 请参阅 this related question。使用dplyr，您可以使用case_when，这可能是您正在寻找的：

library(dplyr)
library(leaflet)

leafIcons <- icons(
  iconUrl = case_when(
    quakes1$mag <= 4.3 ~ "http://leafletjs.com/examples/custom-icons/leaf-green.png",
    4.3 < quakes1$mag & quakes1$mag <= 5 ~ "http://leafletjs.com/examples/custom-icons/leaf-orange.png",
    quakes1$mag > 5 ~ "http://leafletjs.com/examples/custom-icons/leaf-red.png"
  ),
  iconWidth = 38, iconHeight = 95,
  iconAnchorX = 22, iconAnchorY = 94,
  shadowUrl = "http://leafletjs.com/examples/custom-icons/leaf-shadow.png",
  shadowWidth = 50, shadowHeight = 64,
  shadowAnchorX = 4, shadowAnchorY = 62
)

如果您想要将图标分配给不同范围的数字向量，也可以使用cut 或findInterval。