r - Shiny 的应用程序 - ggplot 找不到数据

Question

我制作了一个 Shiny 的应用程序，它使用 ggmap 将静态 map 带回来。
但是，当我想覆盖邮政编码边界时，我遇到了 ggplot 找不到数据集的错误。

数据集 poa 是邮政编码边界的数据框，即具有多边形 ID 的纬度和经度。
我已经尝试添加 environment = environment()但这并不能解决我的问题。
我知道数据存在，因为我打电话 print(str(poa))打印到 R 控制台。

任何人都可以为我建议一个解决方法，以便 ggplot 可以访问 poa 数据框？
我很抱歉这不是一个非常可重复的示例。

更新:
当我使用此代码时，ggplot 能够访问 poa 数据框:

print(ggmap(map)) + geom_polygon(data = poa, aes(x = LON, y = LAT, group = order), alpha = .5, colour = "black", fill = NA))

但是我需要为 map 的基础层对 ggplot 进行嵌套调用，当我这样做时，ggplot 无法找到数据

这是我的 server.R 代码

我正在使用隔离，因为我的 ui.R 中有一个操作按钮，我只希望绘图在单击时更新。

library(shiny)
library(ggmap)
library(RODBC)

# Define server logic required to summarize and view the selected dataset
shinyServer(function(input, output) {

output$searchString <- renderText({
    if (input$searchButton == 0)
        return()        
    isolate({input$searchString})
})

mapSourceInput <- reactive({
    switch(input$mapSource
           , "google" = "google"
           , "stamen" = "stamen")
})

mapTypeInput <- reactive({
    switch(input$mapType
           , "terrain" = "terrain"
           , "satellite" = "satellite"
           , "roadmap" = "roadmap"
           , "hybrid" = "hybrid"
           , "toner" = "toner"
           , "watercolor" = "watercolor")
})

overlayInput <- reactive({
    switch(input$overlay
           , "postcodes" = "postcodes"
           , "states" = "states"
           , "nothing" = "nothing")
})

output$map <- renderPlot({
    if (input$searchButton == 0)
        return()

    isolate({
        if (overlayInput() == "nothing"){
            map <- get_map(location = input$searchString, zoom = input$zoom, source = mapSourceInput(), maptype = mapTypeInput())  
            mapPlot <- ggmap(map)
            print(mapPlot)
            #return()            
        } else {
            if (overlayInput() == "postcodes"){
                #postcode boundaries
                map <- get_map(location = input$searchString, zoom = input$zoom, source = mapSourceInput(), maptype = mapTypeInput())  
                poa <- structure(list(POAOBS = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L)
                               , COORD_REF = 1:10
                               , COORD_POL = 1:10
                               , POLYGON = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L)
                               , LON = c(144.951431274414, 144.956451416016, 144.95539855957, 144.955993652344, 144.958465576172, 144.956634521484, 144.956817626953, 144.954727172852, 144.957550048828, 144.958831787109)
                               , LAT = c(-37.8131675720215, -37.8117561340332, -37.8094863891602, -37.8058776855469, -37.8061485290527, -37.8021659851074, -37.8010902404785, -37.7994079589844, -37.7997169494629, -37.799861907959)
                               , POA = c("3000", "3000", "3000", "3000", "3000", "3000", "3000", "3000", "3000", "3000"))
                          , .Names = c("POAOBS", "COORD_REF", "COORD_POL", "POLYGON", "LON", "LAT", "POA")
                          , row.names = c(NA, 10L)
                          , class = "data.frame")

                print(str(poa))

                print(ggmap(map, base_layer = ggplot(data = poa, aes(x = LON, y = LAT), environment = environment()), extent = "normal", maprange = FALSE, environment = .GlobalEnv) +
                          geom_polygon(data = poa, aes(x = LON, y = LAT, group = order), alpha = .5, colour = "black", fill = NA) +   
                          coord_map(projection = "mercator", 
                                    xlim = c(attr(map, "bb")$ll.lon, attr(map, "bb")$ur.lon),
                                    ylim = c(attr(map, "bb")$ll.lat, attr(map, "bb")$ur.lat)))

            } else {
                if(overlayInput() == "states"){
                    return()
                }}}
    })
})

})

编辑:添加 ui.R

library(shiny)
# Define UI for dataset viewer application
shinyUI(pageWithSidebar(

# Application title.
headerPanel("The New Map App"),

# Sidebar with controls
sidebarPanel(        
    textInput("searchString", "Get Map Of", value = "melbourne, australia") 

    , selectInput("mapSource", "Choose a Map Source", choices = c("google", "stamen"))

    , numericInput("zoom", "Zoom Level", 10)

    , helpText("Note: An integer from 3 (continent) to 21 (building), default value 10 (city)")

    , selectInput("mapType", "Choose a Map Type", choices = c("terrain", "satellite", "roadmap", "hybrid", "toner", "watercolor"))

    , helpText("Note: Options available are 'terrain', 'satellite', 'roadmap', and 'hybrid' (google maps), 'watercolor', and 'toner' (stamen maps)")

    , radioButtons("overlay", "Overlay Polygon",
                   list("Postcodes" = "postcodes"
                        , "States" = "states"
                        , "Nothing" = "nothing"))

    , actionButton("searchButton", "Get Map")
    , tags$style(type='text/css', "button#searchButton { margin-bottom: 9px; }")
),

#output panel
mainPanel(
    h3(textOutput("searchString"))
    , plotOutput("map")

)
))

sessionInfo 的输出:

R version 3.0.1 (2013-05-16)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_AU.UTF-8       LC_NUMERIC=C               LC_TIME=en_AU.UTF-8            LC_COLLATE=en_AU.UTF-8     LC_MONETARY=en_AU.UTF-8   
 [6] LC_MESSAGES=en_AU.UTF-8    LC_PAPER=C                 LC_NAME=C                      LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_AU.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] RODBC_1.3-7     ggmap_2.3       ggplot2_0.9.3.1 shiny_0.6.0    

loaded via a namespace (and not attached):
 [1] bitops_1.0-5        caTools_1.14        colorspace_1.2-2    dichromat_2.0-0         digest_0.6.3        grid_3.0.1         
 [7] gtable_0.1.2        httpuv_1.0.6.3      labeling_0.1            mapproj_1.2-1           maps_2.3-2          MASS_7.3-26        
[13] munsell_0.4         plyr_1.8            png_0.1-5           proto_0.3-10            RColorBrewer_1.0-5  Rcpp_0.10.4        
[19] reshape2_1.2.2      RgoogleMaps_1.2.0.3 rjson_0.2.12        RJSONIO_1.0-3       scales_0.2.3        stringr_0.6.2      
[25] tools_3.0.1         xtable_1.7-1   

Answer 1

所以我终于想通了这一点。

为了让 ggplot 能够在嵌套的 ggplot 查询中找到数据集，需要使用 <<-

例如，在函数内部调用时，无法在此嵌套查询中找到数据集 poa。

print(ggmap(map)) + geom_polygon(data = poa, aes(x = LON, y = LAT, group = order), alpha = .5, colour = "black", fill = NA))

所以在你需要在函数中使用 poa 之前使用这一行

poa <<- poa

从帮助:
“运算符 <<- 和 ->> 通常仅用于函数中，并导致通过父环境搜索被分配变量的现有定义。”