我有一個閃亮的功能,其中用戶選擇下載圖像類型(.png,.tiff等),並點擊一個按鈕下載它的一部分。但所有的選項下載.png格式,我似乎無法找出什麼是錯的。R閃亮下載不同的圖像格式
請注意,預覽總是png。下載功能在點擊按鈕時創建不同的文件類型。另一點需要注意的是在downloadhandler中使用file.copy()而不是像 png(name) plot() dev.off() 這是因爲我的繪圖函數很複雜,file.copy()是更實用。 代碼如下。
#ui.R ----------------------------------------------------------
shinyUI(fluidPage(
titlePanel("Download test"),
sidebarLayout(
sidebarPanel(
numericInput("fheight", "Height (cm)", min=2, max=15, step=1, value = 10),
numericInput("fwidth", "Width (cm)", min=2, max=15, step=1, value = 10),
selectInput("fres", "Res", choices=c("100","200","300"), selected = "100"),
selectInput("fformat", "File type", choices=c("png","tiff","jpeg","pdf"), selected = "png", multiple = FALSE, selectize = TRUE),
downloadButton('bn_download', 'Download Plot')
),
# Show a plot of the generated distribution
mainPanel(
imageOutput("plotoutput")
)
)
))
# server.R ----------------------------------------------------------
shinyServer(function(input, output) {
# store some values
store <- reactiveValues(dname="AwesomeDownload")
# data creation
fn_data <- reactive({
df <- data.frame(x=rnorm(50),y=rnorm(50))
})
# create filename
fn_downloadname <- reactive({
if(input$fformat=="png") filename <- paste0(store$dname,".png",sep="")
if(input$fformat=="tiff") filename <- paste0(store$dname,".tif",sep="")
if(input$fformat=="jpeg") filename <- paste0(store$dname,".jpg",sep="")
if(input$fformat=="pdf") filename <- paste0(store$dname,".pdf",sep="")
return(filename)
})
# render png preview
output$plotoutput <- renderImage({
df <- fn_data()
fheight <- input$fheight
fwidth <- input$fwidth
fres <- as.numeric(input$fres)
png(paste0(store$dname,".png",sep=""), height=fheight, width=fwidth, res=fres, units="cm")
plot(df)
dev.off()
return(list(src = paste0(store$dname,".png",sep=""),
contentType = "image/png",
width = round((input$fwidth*as.numeric(input$fres))/2.54, 0),
height = round((input$fheight*as.numeric(input$fres))/2.54, 0),
alt = "plot"))
},deleteFile=TRUE)
# download function
fn_download <- function()
{
df <- fn_data()
fheight <- input$fheight
fwidth <- input$fwidth
fres <- as.numeric(input$fres)
if(input$fformat=="pdf") fheight <- round(fheight*0.3937,2)
if(input$fformat=="pdf") fwidth <- round(fwidth*0.3937,2)
if(input$fformat=="png") png(fn_downloadname(), height=fheight, width=fwidth, res=fres, units="cm")
if(input$fformat=="tiff") tiff(fn_downloadname(), height=fheight, width=fwidth, res=fres, units="cm",compression="lzw")
if(input$fformat=="jpeg") jpeg(fn_downloadname(), height=fheight, width=fwidth, res=fres, units="cm",quality=100)
if(input$fformat=="pdf") pdf(fn_downloadname(), height=fheight, width=fwidth)
plot(df)
dev.off()
}
# download handler
output$bn_download <- downloadHandler(
filename = fn_downloadname(),
content = function(file) {
fn_download()
file.copy(fn_downloadname(), file, overwrite=T)
}
)
})
這裏https://groups.google.com/forum/#一起來看看! topic/shiny-discuss/u7gwXc8_vyY –