从 Shiny (R) 下载 png [英] Downloading png from Shiny (R)
问题描述
我对 Shiny(和 R)非常陌生,正在努力将我在 Shiny 中制作的图导出到 png 文件.
I am pretty new to Shiny (and R) and struggling with exporting the plot I make in Shiny to a png-file.
我查看了这两个线程,但无法弄清楚:
I looked at these two threads but could not figure it out:
保存在闪亮应用中制作的绘图Shiny downloadHandler 不保存 PNG 文件
我设法在 ui 中创建了下载按钮,服务器似乎也在做我想让它做的一切.当我点击预览窗口中的下载按钮时,会弹出一个窗口,要求我指定文件位置和名称,但没有保存文件.当我在浏览器窗口中做同样的事情时,会创建一个 png 文件,但它是空的.
I manage to create the download button in the ui and the server seems to be doing everything I want it to do, too. When I hit the download button in the preview window, a pop up window asks me to specify the file location and name but no file is saved. When I do the same in a browser window, a png file is created but it is empty.
非常感谢任何见解!
ui.R
library(shiny)
shinyUI(fluidPage(
titlePanel("This is a scatterplot"),
sidebarLayout(
sidebarPanel(
fileInput('datafile', 'Choose CSV file',
accept=c('text/csv', 'text/comma-separated-values,text/plain')),
uiOutput("varselect1"),
uiOutput("varselect2"),
downloadButton('downloadPlot', 'Download Plot')
),
mainPanel(
h4("Here is your scatterplot"),
plotOutput("plot1")
)
))
)
server.R
library(foreign)
shinyServer(function(session,input, output) {
DataInput <- reactive({
infile <- input$datafile
if (is.null(infile)) {
return(NULL)
}
read.csv(infile$datapath)
})
output$varselect1 <- renderUI({
if (identical(DataInput(), '') || identical(DataInput(),data.frame())) return(NULL)
cols <- names(DataInput())
selectInput("var1", "Select a variable:",choices=c("---",cols[3:length(cols)]), selected=("---"))
})
output$varselect2 <- renderUI({
if (identical(DataInput(), '') || identical(DataInput(),data.frame())) return(NULL)
cols <- names(DataInput())
selectInput("var2", "Select a variable:",choices=c("---",cols[3:length(cols)]), selected=("---"))
})
plotInput <- reactive({
a <- which(names(DataInput())==input$var1)
x_lab <- as.numeric(DataInput()[,a])
b <- which(names(DataInput())==input$var2)
y_lab <- as.numeric(DataInput()[,b])
main.text <- paste("Scatterplot of the variables",colnames(DataInput())[a],"and", colnames(DataInput())[b],sep = " ", collapse = NULL)
plot(x_lab, y_lab, main=main.text, xlab=colnames(DataInput())[a], ylab=colnames(DataInput())[b], xlim=c(min(x_lab),max(x_lab)*1.05), ylim=c(min(y_lab), max(y_lab)*1.05))
observations <- DataInput()[,1]
text(x_lab, y_lab, labels=observations, pos=3)
})
output$plot1 <- renderPlot({
print(plotInput())
})
output$downloadPlot <- downloadHandler(
filename = "Shinyplot.png",
content = function(file) {
png(file)
print(plotInput())
dev.off()
})
})
推荐答案
在 闪亮讨论谷歌群组.您可以做的只是将反应式 plotInput
语句更改为普通函数.不知道为什么 downloadHandler
不能很好地处理响应式对象.
A workaround for this strange scenario was discussed on the shiny-discuss google group. What you can do is simply change your reactive plotInput
statement into a normal function. Not sure why downloadHandler
doesn't play nice with reactive objects.
# change
plotInput <- reactive({...})
# into this
plotInput <- function(){...}
您也可以删除downloadHandler
调用中的print语句:
You can also remove the print statement in the downloadHandler
call:
output$downloadPlot <- downloadHandler(
filename = "Shinyplot.png",
content = function(file) {
png(file)
plotInput()
dev.off()
})
这篇关于从 Shiny (R) 下载 png的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!