保存在闪亮的应用程序中制作的图 [英] Save plots made in a shiny app

问题描述

我想弄清楚如何使用 downloadButton 来保存一个闪亮的情节.包中的示例演示了用于保存 .csv 文件的 downloadButton/downloadHandler.我将在此基础上制作一个可重现的示例.

I'm trying to figure out how to use downloadButton to save a plot with shiny. The example in the package demonstrates downloadButton/downloadHandler to save a .csv. I'm going to make a reproducible example based on that.

对于 ui.R

shinyUI(pageWithSidebar(
  headerPanel('Downloading Data'),
  sidebarPanel(
selectInput("dataset", "Choose a dataset:", 
            choices = c("rock", "pressure", "cars")),
    downloadButton('downloadData', 'Download Data'),
    downloadButton('downloadPlot', 'Download Plot')
  ),
  mainPanel(
    plotOutput('plot')
  )
))

对于 server.R

library(ggplot2)
shinyServer(function(input, output) {
  datasetInput <- reactive({
    switch(input$dataset,
           "rock" = rock,
           "pressure" = pressure,
           "cars" = cars)
  })

  plotInput <- reactive({
    df <- datasetInput()
    p <-ggplot(df, aes_string(x=names(df)[1], y=names(df)[2])) +
      geom_point()
  })

  output$plot <- renderPlot({
    print(plotInput())
  })

  output$downloadData <- downloadHandler(
    filename = function() { paste(input$dataset, '.csv', sep='') },
    content = function(file) {
      write.csv(datatasetInput(), file)
    }
  )
  output$downloadPlot <- downloadHandler(
    filename = function() { paste(input$dataset, '.png', sep='') },
    content = function(file) {
      ggsave(file,plotInput())
    }
  )
})

如果您正在回答这个问题，您可能对此很熟悉，但要使其正常工作，请将上述内容保存到单独的脚本中(ui.R 和 server.R 放入工作目录中的文件夹 (foo).要运行闪亮的应用程序，请运行 runApp("foo").

If you're answering this question, you are probably familiar with this, but to get this working, save the above into separate scripts (ui.R and server.R into a folder (foo) within the working directory. To run the shiny app, run runApp("foo").

使用 ggsave，我收到一条错误消息，指出 ggsave 不能使用 filename 函数(我认为).如果我使用标准图形设备(如下所示)，Download Plot 可以正常工作，但不会写入图形.

Using ggsave, I get an error message indicating that ggsave can't use the filename function (I think). If I use the standard graphics device (like below), the Download Plot works without an error, but it doesn't write the graphic.

任何让 downloadHandler 用于编写绘图的提示将不胜感激.

Any tips to get downloadHandler working for writing plots would be appreciated.

推荐答案

不确定这个问题是否仍然有效，但它是搜索在闪亮的应用程序中保存绘图"时出现的第一个问题，所以我想快速添加如何按照原始问题的思路让 ggsave 与 downloadHandler 一起工作.

Not sure if this question is still active but it's the first one that came up when searching for "saving plots in shiny app" so I wanted to quickly add how to get ggsave to work with downloadHandler along the lines of the original question.

juba 建议的使用直接输出而不是 ggsave 的替代策略和 alexwhan 自己建议的替代策略都很好用，这仅适用于那些绝对想在 downloadHandler 中使用 ggsave 的人).

The alternative strategies suggested by juba using direct output instead of ggsave and alternative strategy suggested by alexwhan himself both work great, this is just for those who absolutely want to use ggsave in the downloadHandler).

alexwhan 报告的问题是由 ggsave 尝试将文件扩展名匹配到正确的图形设备引起的.但是，临时文件没有扩展名，因此匹配失败.这可以通过在 ggsave 函数调用中专门设置设备来解决，就像在原始代码示例(对于 png)中一样:

The problem reported by alexwhan is caused by ggsave trying to match the file extension to the correct graphics device. The temporary file, however, doesn't have an extension so the matching fails. This can be remedied by specifically setting the device in the ggsave function call, like so in the original code example (for a png):

output$downloadPlot <- downloadHandler(
    filename = function() { paste(input$dataset, '.png', sep='') },
    content = function(file) {
        device <- function(..., width, height) grDevices::png(..., width = width, height = height, res = 300, units = "in")
        ggsave(file, plot = plotInput(), device = device)
    }
)

这个调用基本上将device函数用于ggsave内部分配的png(你可以查看ggsavecode> 函数代码以查看jpg、pdf 等的语法).也许，理想情况下，可以将文件扩展名(如果与文件名不同 - 就像这里的临时文件一样)指定为 ggsave 参数，但此选项目前在 中不可用ggsave.

This call basically takes the device function for a png that ggsave assigns internally (you can look at the ggsave function code to see the syntax for jpg, pdf, etc). Perhaps, ideally, one could specify the file extension (if different from the file name - as is the case here for the temporary file) as a ggsave parameter but this option is currently not available in ggsave.

一个最小的独立工作示例:

A minimal self-contained working example:

library(shiny)
library(ggplot2)
runApp(list(
  ui = fluidPage(downloadButton('foo')),
  server = function(input, output) {
    plotInput = function() {
      qplot(speed, dist, data = cars)
    }
    output$foo = downloadHandler(
      filename = 'test.png',
      content = function(file) {
        device <- function(..., width, height) {
          grDevices::png(..., width = width, height = height,
                         res = 300, units = "in")
        }
        ggsave(file, plot = plotInput(), device = device)
      })
  }
))

sessionInfo()
# R version 3.1.1 (2014-07-10)
# Platform: x86_64-pc-linux-gnu (64-bit)
# 
# locale:
#  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
#  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
#  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
#  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
#  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
# [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
# 
# attached base packages:
# [1] stats     graphics  grDevices utils     datasets  methods   base     
# 
# other attached packages:
# [1] ggplot2_1.0.0 shiny_0.10.1 
# 
# loaded via a namespace (and not attached):
#  [1] bitops_1.0-6     caTools_1.17     colorspace_1.2-4 digest_0.6.4    
#  [5] formatR_1.0      grid_3.1.1       gtable_0.1.2     htmltools_0.2.6 
#  [9] httpuv_1.3.0     labeling_0.2     MASS_7.3-34      munsell_0.4.2   
# [13] plyr_1.8.1       proto_0.3-10     Rcpp_0.11.2      reshape2_1.4    
# [17] RJSONIO_1.3-0    scales_0.2.4     stringr_0.6.2    tools_3.1.1     
# [21] xtable_1.7-3    

更新

从 ggplot2 2.0.0 版本开始，ggsave 函数支持 device 参数的字符输入，这意味着由 downloadHandler 创建的临时文件现在可以用通过指定要使用的扩展名直接调用 ggsave"pdf"(而不是传入设备函数).这将上面的例子简化为以下

Update

As of ggplot2 version 2.0.0, the ggsave function supports character input for the device parameter, that means the temporary file created by the downloadHandler can now be saved with a direct call to ggsave by specifying that the extension to be used should be e.g. "pdf" (rather than passing in a device function). This simplifies the above example to the following

output$downloadPlot <- downloadHandler(
    filename = function() { paste(input$dataset, '.png', sep='') },
    content = function(file) {
        ggsave(file, plot = plotInput(), device = "png")
    }
)

这篇关于保存在闪亮的应用程序中制作的图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！