根据输入更改传单地图，而无需重新绘制 [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更改Shiny和Leaflet以根据输入的变化来绘制点.
I'm wondering how I can change Shiny and Leaflet to plot points according to the change in input without redrawing the whole map.
我正在使用的代码是:
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)
The dataset used for the code is available at this link - Melbourne Urban Forest Data
有很多要点，所以我不想每次更改输入时都重新绘制.输入基于数据集中的"Precinct"列.我们对这里的任何帮助深表感谢.
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
好吧，你去了:leafletProxy用于向现有的传单地图中添加图层.用法和普通的传单添加一样，但是您不需要呈现部分，因为地图已经在文档中呈现了.
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，即图块，图例，静态图形以及您只想做的所有事情.这是您的起点.从那里开始，仅通过直接命令而不是重新渲染来更改地图.
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来访问此地图.在极少数情况下，我们有leafletOutput("treedat")，因此，如果要寻址此地图，请使用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，而无需重新渲染它.
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/必须在某些observe语句内部进行，而不是在renderLeaflet内部进行.请注意，每个命令都是原始映射的补充，这就是为什么我在下面的示例中必须使用clearMarkers的原因.
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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