在 R shiny 中调用 downloadHandler 函数时，如何生成带有选择提示的弹出窗口，提示下载哪个对象?

Question

在下面的 MWE 代码中，downloadHandler成功地允许用户下载下面函数vectorVariable(input$base_input[1,1],vector1_input())中定义的第一个绘图"vector1"。但是，我正在尝试修改以下内容，以便在单击下载按钮时，通过弹出窗口提示用户下载 vector1 或 vector2，后者在下面函数vectorVariable(input$base_input[2,1],vector2_input())中定义。

有人可以帮我编写一个条件弹出窗口，其中包含某种selectInput或类似下载对象，通过单击下载按钮触发？

我试图坚持使用本机 Shiny 函数downloadHandler因为它在提示用户选择下载目录方面做得很好。我发现这很难在downloadHandler之外做到。

请注意，在此 MWE 派生的完整应用程序中，有两个以上的 PNG 文件可供选择下载。此外，在完整的应用程序中，相同的下载按钮用于此 MWE 中未显示的单独server部分，用于下载数据表(运行良好)，---因此对象下载选择的任何更改都需要在server部分中完成，保持UI部分中的downloadButton("download", "Download")不变，因为它处理的不仅仅是此 MWE 中显示的这些 PNG 文件(我想这意味着某种renderUI...

MWE代码：

library(shiny)
library(shinyMatrix)
library(shinyjs)
library(DT)
matrix1.input <- function(x){
matrixInput(x, 
value = matrix(c(0.2), 2, 1, dimnames = list(c("A","B"),NULL)),
rows = list(extend = FALSE,  names = TRUE),
cols = list(extend = FALSE, names = FALSE, editableNames = FALSE),
class = "numeric")}
matrix2.input <- function(x,y,z){
matrixInput(x,
value = matrix(c(y,z),1,2,dimnames=list(NULL,c("Y","Z"))),
rows = list(extend = TRUE,  names = FALSE),
cols = list(extend = FALSE, names = TRUE, editableNames = FALSE),
class = "numeric")}  
matrix.validate <- function(x,y){
a <- y        
a[,1][a[,1]>x] <- x 
b <- diff(a[,1,drop=FALSE]) 
b[b<=0] <- NA               
b <- c(1,b)                 
a <- cbind(a,b)
a <- na.omit(a) 
a <- a[,-c(3),drop=FALSE]         
return(a)}
vector.base <- function(x,y){
a <- rep(y,x) 
b <- seq(1:x) 
c <- data.frame(x = b, y = a) 
return(c)}
vector.multi <- function(x,y,z){                                            
a <- rep(NA, x)
a[y] <- z       
a[seq_len(min(y)-1)] <- a[min(y)] 
if(max(y) < x){a[seq(max(y)+1, x, 1)] <- 0}   
a <- approx(seq_along(a)[!is.na(a)],a[!is.na(a)],seq_along(a))$y  
b <- seq(1:x)                                                     
c <- data.frame(x = b, z = a)                                     
return(c)}
vector.multiFinal <- function(x,y){
vector.multi(x,matrix.validate(x,y)[,1],matrix.validate(x,y)[,2])}
matrix.link <- function(x,y){
observeEvent(input$periods|input$base_input,{
updateMatrixInput(session,x,value=matrix(c(input$periods,y),1,2,dimnames=list(NULL, c("y","z"))))})}
ui <- 
pageWithSidebar(
headerPanel("Model"),
sidebarPanel(uiOutput("Panels")),
mainPanel(
tabsetPanel(
tabPanel("Dynamic", value=2,
actionButton('showVectorPlotBtn','Vector plots'),
actionButton('showVectorValueBtn','Vector values'),

downloadButton("download", "Download"),

uiOutput("vectorTable")),
id = "tabselected")
) # close main panel
) # close page with sidebar
server <- function(input,output,session)({
periods       <- reactive(input$periods)
base_input    <- reactive(input$base_input)
vector1_input <- reactive(input$vector1_input)
vector2_input <- reactive(input$vector2_input)
yld           <- reactiveValues()

vectorVariable <- function(x,y){
if(input$showVectorBtn == 0) vector.base(input$periods,x)
else vector.multiFinal(input$periods,matrix.validate(input$periods,y))}

output$Panels <- renderUI({
tagList( 
conditionalPanel(
condition="input.tabselected==2",
sliderInput('periods','',min=1,max=120,value=60),
matrix1.input("base_input"),
useShinyjs(),
actionButton('showVectorBtn','Show'), 
actionButton('hideVectorBtn','Hide'),
actionButton('resetVectorBtn','Reset'),
hidden(uiOutput("Vectors"))))})

renderUI({
matrix.link("vector1_input",input$base_input[1,1])
matrix.link("vector2_input",input$base_input[2,1])})

output$Vectors <- renderUI({input$resetVectorBtn
tagList(matrix2.input("vector1_input",input$periods,input$base_input[1,1]),
matrix2.input("vector2_input",input$periods,input$base_input[2,1]))})

observeEvent(input$showVectorBtn,{shinyjs::show("Vectors")})
observeEvent(input$hideVectorBtn,{shinyjs::hide("Vectors")})

output$graph1 <- renderPlot(plot(vectorVariable(input$base_input[1,1],vector1_input())))
output$graph2 <- renderPlot(plot(vectorVariable(input$base_input[2,1],vector2_input())))

output$download <- downloadHandler(
filename = function() {paste("vector1","png",sep=".")},
content = function(file){
png(file)
plot(vectorVariable(input$base_input[1,1],vector1_input()))
dev.off()}
) # close download handler

output$table1 <- renderDT({vectorsAll()})

observeEvent(input$showVectorPlotBtn,{yld$showme <- tagList(plotOutput("graph1"), plotOutput("graph2"))},ignoreNULL = FALSE)
observeEvent(input$showVectorValueBtn,{yld$showme <- DTOutput("table1")})

output$vectorTable <- renderUI({yld$showme})

vectorsAll <- reactive({
cbind(1:periods(),
vectorVariable(input$base_input[1,1],vector1_input())[,2],
vectorVariable(input$base_input[2,1],vector2_input())[,2])})})
shinyApp(ui, server)

Answer 1

为了回应ismirsehregal的评论，下面是使用ActionButton的工作MWE触发一个模态，并在所述模态中插入了选择输入和下载按钮。这是伊斯米尔塞雷加尔的干净解决方案。

MWE 代码(为了简洁起见，省略了原始 MWE 中的库和函数定义;如果您想在下面运行此 MWE，请确保从上面复制库和定义的函数！！

ui <- 
pageWithSidebar(
headerPanel("Model"),
sidebarPanel(uiOutput("Panels")),
mainPanel(
tabsetPanel(
tabPanel("Dynamic", value=2,
actionButton('showVectorPlotBtn','Vector plots'),
actionButton('showVectorValueBtn','Vector values'),

actionButton("showDownload", "Download"),

uiOutput("vectorTable")),
id = "tabselected")
) # close main panel
) # close page with sidebar
server <- function(input,output,session)({
periods       <- reactive(input$periods)
base_input    <- reactive(input$base_input)
vector1_input <- reactive(input$vector1_input)
vector2_input <- reactive(input$vector2_input)
yld           <- reactiveValues()

vectorVariable <- function(x,y){
if(input$showVectorBtn == 0) vector.base(input$periods,x)
else vector.multiFinal(input$periods,matrix.validate(input$periods,y))}

output$Panels <- renderUI({
tagList( 
conditionalPanel(
condition="input.tabselected==2",
sliderInput('periods','',min=1,max=120,value=60),
matrix1.input("base_input"),
useShinyjs(),
actionButton('showVectorBtn','Show'), 
actionButton('hideVectorBtn','Hide'),
actionButton('resetVectorBtn','Reset'),
hidden(uiOutput("Vectors"))))})

renderUI({
matrix.link("vector1_input",input$base_input[1,1])
matrix.link("vector2_input",input$base_input[2,1])})

output$Vectors <- renderUI({input$resetVectorBtn
tagList(matrix2.input("vector1_input",input$periods,input$base_input[1,1]),
matrix2.input("vector2_input",input$periods,input$base_input[2,1]))})

observeEvent(input$showVectorBtn,{shinyjs::show("Vectors")})
observeEvent(input$hideVectorBtn,{shinyjs::hide("Vectors")})

output$graph1 <- renderPlot(plot(vectorVariable(input$base_input[1,1],vector1_input())))
output$graph2 <- renderPlot(plot(vectorVariable(input$base_input[2,1],vector2_input())))

output$download <- downloadHandler(
filename = function() {
if (input$downloadItem == "Vector1") {paste("Vector1","png",sep=".")}
else {paste("Vector2","png",sep=".")}
},
content = function(file){
png(file)
if (input$downloadItem == "Vector1"){plot(vectorVariable(input$base_input[1,1],vector1_input()))}
else {plot(vectorVariable(input$base_input[2,1],vector2_input()))}
dev.off()}
) # close download handler

observeEvent(input$showDownload,
{showModal(modalDialog(
selectInput("downloadItem","Select item to download:",
c("Vector1","Vector2")),
downloadButton("download", "Download")

) # close modalDialog
) # close showModal
} # close showModal function
) # close observeEvent

output$table1 <- renderDT({vectorsAll()})

observeEvent(input$showVectorPlotBtn,{yld$showme <- tagList(plotOutput("graph1"), plotOutput("graph2"))},ignoreNULL = FALSE)
observeEvent(input$showVectorValueBtn,{yld$showme <- DTOutput("table1")})

output$vectorTable <- renderUI({yld$showme})

vectorsAll <- reactive({
cbind(1:periods(),
vectorVariable(input$base_input[1,1],vector1_input())[,2],
vectorVariable(input$base_input[2,1],vector2_input())[,2])})})
shinyApp(ui, server)