根据输入更改传单地图而不重绘 [英] Changing Leaflet map according to input without redrawing
问题描述
我想知道如何在不重绘整个地图的情况下根据输入的变化将 Shiny 和 Leaflet 更改为绘图点.
I'm wondering how I can change Shiny and Leaflet to plot points according to the change in input without redrawing the whole map.
我使用的代码是:
library(leaflet)
library(shiny)
library(dplyr)
library(readr)
ui <- fluidPage(
titlePanel("Melbourne Urban Tree Visualisation"),
leafletOutput("treedat"),
uiOutput("precinct")
#Giving an input name and listing out types to choose in the Shiny app
)
server <- function(input, output){
#td <- read.csv("treedata.csv", header = TRUE)
#pal <- colorNumeric(
#palette = "RdYlGn",
#domain = td$LifeExpectencyValue
#)
output$precinct <- renderUI({
choices <- as.character(unique(td$Precinct))
choices <- c('All', choices)
selectInput(inputId = "precinct", label = "Precinct", choices = choices, selected = "CBD")
})
output$treedat <- renderLeaflet({
#if(is.null(td)) return()
## get the choice from teh drop-down box
PRECINCT = input$precinct
## supbset the data based on the choice
if(PRECINCT != 'All'){
td2 <- td[td$Precinct == PRECINCT, ]
}else{
td2 <- td
}
## plot the subsetted ata
td2 <- leafletProxy(td2) %>% addTiles(
urlTemplate = 'http://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png',
attribution='Map tiles by <a href="http://stamen.com">Stamen Design</a>, <a href="http://creativecommons.org/licenses/by/3.0">CC BY 3.0</a> — Map data © <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>') %>%
addCircleMarkers(radius= 5,
fillOpacity = 0.5,
stroke = FALSE,
color=~pal(LifeExpectencyValue),
popup=paste("<b>", td$CommonName,"</b>", "<br>",
"<b>","Years Left:", "</b>", td$LifeExpectency, "<br>",
"<b>","Genus:","</b>", td$Genus)) %>% addLegend(pal = pal,
values = ~LifeExpectencyValue,
opacity = 1,
title = "Life Expectency")
return(td2)
})
}
shinyApp(ui = ui, server = server)
用于代码的数据集可在此链接获得 - 墨尔本城市森林数据
The dataset used for the code is available at this link - Melbourne Urban Forest Data
有很多点，所以我不想每次输入更改时都重新绘制.输入基于区域".数据集中的列.非常感谢这里的任何帮助.
There are a lot of points so I wouldn't want to re-draw each time the input is changed. The input is based on the "Precinct" column in the dataset. Any help here is deeply appreciated.
推荐答案
好的，你去吧:leafletProxy 用于向现有的传单地图添加图层.用法就像普通的传单添加一样，但您不需要渲染部分，因为地图已经在您的文档中渲染.
Okay, there you go: leafletProxy is used to add layers to an existing leaflet map. The usage ist just like normal leaflet additions, but you don't need the rendering part, since the map is already rendered in your document.
第一个也是最简单的部分是在基本级别上渲染传单地图，即瓷砖、图例、静态图纸，所有你想做的事情都只做一次.这是你的起点.从那以后，改变地图只能通过直接命令而不是重新渲染来完成.
The first and easiest part is to render the leaflet map on a basic level, that is tiles, legend, static drawings, everything that you want to do just once. This is your starting point. From there on, altering the map is only done by direct commands instead of re-renderings.
现在可以通过其闪亮的输出 ID 访问此地图.在这种情况下，我们有 leafletOutput("treedat")，所以如果我们想处理这张地图，我们使用 leafletProxy("treedat").我们使用与常规传单修改相同的语法.例如.leafletProxy("treedat") %>% addMarkers(lat = 1, lng = 1) 将标记添加到现有地图而不重新渲染它.
This map can now be accessed via its shiny output id. In out case, we had leafletOutput("treedat"), so if we want to address this map, we use leafletProxy("treedat"). We use the same syntax as in regular leaflet modifications. E.g. leafletProxy("treedat") %>% addMarkers(lat = 1, lng = 1) adds a marker to the existing map without re-rendering it.
因此，对地图的每次修改都可以/必须在一些 observe 语句内部进行，而不是在 renderLeaflet 内部进行.请注意，每个命令都是对原始地图的补充，这就是为什么我必须在下面的示例中使用 clearMarkers.
Thus, every modification to the map can / has to happen from inside some observe statement and not from inside the renderLeaflet. Note that every command is an addition to the original map, which is why I had to use clearMarkers in the example below.
代码:
library(leaflet)
library(shiny)
library(dplyr)
library(readr)
ui <- fluidPage(
titlePanel("Melbourne Urban Tree Visualisation"),
leafletOutput("treedat"),
uiOutput("precinct")
#Giving an input name and listing out types to choose in the Shiny app
)
server <- function(input, output){
td <- data.frame(
LifeExpectencyValue = sample(20:100, 10),
Precinct = c(rep("CBD", 3), rep("ABC", 4), rep("XYZ", 3)),
CommonName = sapply(1:10, function(x){paste(sample(LETTERS, 10, replace = TRUE), collapse = "")}),
Genus = rep(c("m","f"), each = 5),
lat = seq(5, 50, 5),
lng = seq(2, 65, 7)
)
pal <- colorNumeric(palette = "RdYlGn", domain = td$LifeExpectencyValue)
output$precinct <- renderUI({
choices <- as.character(unique(td$Precinct))
choices <- c('All', choices)
selectInput(inputId = "precinct", label = "Precinct", choices = choices, selected = "CBD")
})
output$treedat <- renderLeaflet({
leaflet() %>%
addTiles(
urlTemplate = 'http://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png',
attribution='Map tiles by <a href="http://stamen.com">Stamen Design</a>, <a href="http://creativecommons.org/licenses/by/3.0">CC BY 3.0</a> — Map data © <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>'
) %>%
addLegend(pal = pal, values = td$LifeExpectencyValue, opacity = 1, title = "Life Expectency")
})
observeEvent(input$precinct, {
#if(is.null(td)) return()
## get the choice from teh drop-down box
PRECINCT = input$precinct
## supbset the data based on the choice
if(PRECINCT != 'All'){
td2 <- td[td$Precinct == PRECINCT, ]
}else{
td2 <- td
}
## plot the subsetted ata
leafletProxy("treedat") %>%
clearMarkers() %>%
addCircleMarkers(lat = td2$lat, lng = td2$lng,
radius= 5, fillOpacity = 0.5, stroke = FALSE, color=pal(td2$LifeExpectencyValue),
popup = paste("<b>", td2$CommonName,"</b>", "<br>",
"<b>","Years Left:", "</b>", td2$LifeExpectency, "<br>",
"<b>","Genus:","</b>", td2$Genus))
})
}
shinyApp(ui = ui, server = server)
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