如何在地圖上顯示點的圖例（比例尺顏色）？

Question

R版本3.2.3

library(OpenStreetMap) 
map <- openmap(c(lat= 48, lon= 3), c(lat= 40, lon= 0)) 
map <- openproj(map) 
plot(map) 
lon=c(1, 03, 04, 08, -1) 
    lat=c(40, 41, 41, 42, 41) 
    x=c(1, 3, 0.1, 2, 1) #I give here example of only 5 values but my real values are many and vary. So the values here are not discrete but continuous! 

points(lon,lat,pch=19,col=x) #not sure here how 

我想繪製從藍色到紅色，最重要的展會規模顏色（傳說）地圖旁的色彩範圍在地圖上x的這些點。

Answer 1

在你的問題中，你已經使用OpenStreetMap（我無法運行）;你是否反對使用leaflet？

如果沒有，你可以做

library(leaflet) 

df <- data.frame(lon=c(1, 03, 04, 08, -1), 
       lat=c(40, 41, 41, 42, 41), 
       x=c(1, 3, 0.1, 2, 1)) 

pal <- colorNumeric(
    palette = c("#ff0000","#0000ff"), 
    domain = df$x 
) 

leaflet() %>% 
    setView(lng = 3, lat = 48, zoom = 4) %>% 
    addProviderTiles("Esri.WorldGrayCanvas") %>% ## pick any map layer you want 
    addCircleMarkers(data = df, lng = ~lon, lat = ~lat, stroke=FALSE, color=~pal(x), fillOpacity = 0.6) %>% 
    addLegend(position = c("bottomleft"), pal = pal, values = df$x)