嘿!

Today I would like to introduce you to the leaflet package for R. This package makes it easy to integrate and control 传单 地图 in R. In other words: You can create beautiful 传单 地图 with your 数据 from inside R, without any knowledge of 的JavaScript , HTML, CSS, etc…听起来很棒，对吧？这是这样的…
首先让’s prepare some 数据 :

library(raster)
#get boundaries
usa <- getData("GADM", country="USA", level=2)
#add random  数据 
usa$randomData <- rnorm(n=nrow(usa), 150, 30)

The fastest way to get to some arbitrary 数据 , is to load the 栅格 package and download administrative boundaries of a country of your choice using the getData() function. Note that country boundaries come without any additional 数据 (like population, income, etc..). Since we later want to visualise some 数据 on our map using some colors and pop-ups, I added a new column to the SpatialPolygonsDataFrame and filled it with random 数据 using the rnorm function.

创建地图

创建包含传单地图的HTML页面的最简单方法是使用RMarkdown。为此，请转到新文件-> RMarkdown ->HTML。最终的RMarkdown文档如下所示：

---
title: " 传单  with R 101"
output: html_document
---

```{r, echo=F, warning=F, message=F}
#load leaflet package for R
library(leaflet)
library(raster)

#arbitrary  数据  (code from above)
usa <- getData("GADM", country="USA", level=2)
usa$randomData <- rnorm(n=nrow(usa), 150, 30)

#create a color palette to fill the polygons
pal <- colorQuantile("Greens", NULL, n = 5)

#create a pop up (onClick)
polygon_popup <- paste0("<strong>Name: </strong>", usa$NAME_1, "<br>",
                        "<strong>Indicator: </strong>", round(usa$randomData,2))

#create leaflet map
  map = leaflet() %>% 
      addProviderTiles("CartoDB.Positron") %>% 
      setView(-98.35, 39.7,
              zoom = 4) %>% 
      addPolygons(data = usa, 
                  fillColor= ~pal(randomData),
                  fillOpacity = 0.4, 
                  weight = 2, 
                  color = "white",
                  popup = polygon_popup)
map
```

如您所见，代码很短而且很直观：

leaflet() initialises a new leaflet map, tiles/basemape can be added using the addTiles() or addProviderTiles() functions. In my example I included a basemap provided by CartoDB called “Positron”. Once you set the view and the zoom level using the setView() function, you can overlay your 数据 with the addPolygons() function. And that’s it! Click on KnitHTML and view the final result in your browser:

I hope you enjoyed this rather short introduction into the very powerful leaflet package for R. If you are intrested in more detailed tutorials or code examples, please leave a comment below or visit this official R的传单– Introduction.

干杯

马丁