使用SF列调整Leaflet(R)中的边界 [英] Adjusting bounds in Leaflet (R) with sf column
问题描述
我正在Shiny中制作一个小应用程序,其中包含国家和地区的数据,用户可以在其中选择地区.然后的想法是,我在应用程序中拥有的传单地图将放大并专注于所选区域(即用户单击欧洲",地图将放大欧洲).
I'm making a little app in Shiny that holds data for countries and regions, and where users will be able to choose a region. Then the idea is that the leaflet map that I have in the app will zoom in and focus on the chosen region (i.e. user clicks "Europe" and the map zooms in on Europe).
我不知道应该如何使用简单功能geometry
列作为传单地图的过滤器.这是一个简单的示例(我想不是在Shiny中,但是问题并不与Shiny相关).
I can't figure out how I should go about using the simple featuresgeometry
column as the filter for the leaflet map. Here's a simply example (not in Shiny, but the problem is not Shiny-related, I imagine).
library(rnaturalearth)
library(dplyr)
library(leaflet)
# sf data:
earth <- ne_countries(returnclass = "sf") %>%
select(Region = region_un, geometry)
# little dataset:
df <- data_frame(
Region = c("Europe", "Africa", "Asia", "Oceania", "Americas"),
Score = c(0.85, 0.77, 0.81, 0.93, 0.79)
)
# join:
df <- full_join(df, earth)
# simulate what I'm doing in Shiny:
input <- list()
input$region <- "Europe"
df2 <- filter(df, Region == input$region)
leaflet(df2) %>% addTiles()
这将产生:
与使用df
(未过滤的数据帧)相同.关于如何解决这个问题有任何想法吗?我在Shiny/leaflet文档中找不到它.
Which is the same as if I had used df
(the unfiltered dataframe). Any ideas on how I could go about this? I couldn't find it in the Shiny/leaflet docs.
推荐答案
我们可以使用sf::st_coordinates
从df2$geometry
中提取值,获取平均纬度和经度,然后使用leaflet::setView()
专注于我们感兴趣的区域:
We could use sf::st_coordinates
to extract the values from df2$geometry
, get the average latitude and longitude then use leaflet::setView()
to focus on our region of interest:
library(sf)
coords <- st_coordinates(df2$geometry)
lng <- mean(coords[,1])
lat <- mean(coords[,2])
leaflet(df2) %>% addTiles() %>%
setView(lng, lat, zoom = 3) # 3 for "continent" level
有一些特殊的方法可以在主要是leafletProxy()
的Shiny设置中更新leaflet
映射,这些方法在
There are some special methods for updating leaflet
maps in a Shiny setting mainly leafletProxy()
, those are described pretty well in the docs.
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