r语言 - 无法从 shiny 下载.png文件

Question

我正在尝试为我的直方图创建一个下载按钮。 我可以看到下载按钮，但似乎无法正确下载。 它始终下载.htm文件，而不是.png文件。 我正在我的服务器中使用 ggsave 命令。 我尝试使用更传统的方法，但这似乎也不起作用。

library(shiny)
library(plyr)
library(ggplot2)
shinyUI(fluidPage(
headerPanel(title = "Test"),
sidebarLayout(
sidebarPanel(
sliderInput("input.a", "A", min = 0, max = 100, value = 50),
sliderInput("input.b", "B", min = 0, max = 100, value = 50),
sliderInput("input.c", "C", min = 0, max = 100, value = 50)
),
mainPanel(
tabsetPanel( type = "tabs", #Open panel
tabPanel("Distributions",plotOutput("hist.plot")),
downloadButton('downloadhist', 'Download Plot'))
) # close mainPanel
) # close sidebarLayout
) # close fluidPage
) # close shinyUI
shinyServer(function(input,output){ # open shiny server
#output$hist.plot = renderPlot({ # open renderPlot
make.hist.plot = reactive({
a = runif(1000,1,(input$input.a))
b = runif(1000,1,(input$input.b))
c = runif(1000,1,(input$input.c))
amount = c(a,b,c)
cat = c(rep("a",1000), rep("b",1000), rep("c",1000))
hist.data = data.frame(amount,cat)
names(hist.data) = c("amount","cat")
hist.data$cat = factor(hist.data$cat, levels = c("a","b","c"))
pricedata = ddply(hist.data, c("cat"), summarize, avg = mean(amount), minus.stdev = mean(amount)-sd(amount),
plus.stdev = mean(amount) + sd(amount))
pricedata = pricedata[order(pricedata$avg),]

ggplot(hist.data, aes(x=amount, fill = cat))+
geom_histogram(color="white", alpha = .8, position = 'identity', binwidth = 5)+
theme_test()+
geom_vline(aes(xintercept = avg), data = pricedata, color = "black", size = 1)+

geom_vline(aes(xintercept = minus.stdev), data = pricedata, color = "black", size = .75, linetype = "dotted")+

geom_vline(aes(xintercept = plus.stdev), data = pricedata, color = "black", size = .75, linetype = "dotted")+

facet_grid(cat ~., scales = "free")+
scale_y_continuous(expand = c(0,0),name = "Count")+
scale_x_continuous(labels = scales::dollar, name="nAmount", limits = c(0,100))
}) #close renderPlot
output$hist.plot = renderPlot({
print(make.hist.plot())
})
output$downloadhist = downloadHandler(
filename = function() { "hist.png" },
content = function(file) {
ggsave(file, plot = make.hist.plot(), device = "png")}
)
}) # close shinyServer

Answer 1

这似乎是一个范围问题。如果将下载按钮放在侧边栏面板中，删除tabsetPanel，或者将下载按钮放在同一个tabPanel中，则代码确实有效。最后一个解决方案如下所示：

mainPanel(
tabsetPanel( type = "tabs", #Open panel
tabPanel("Distributions",
plotOutput("hist.plot"),
downloadButton('downloadhist', 'Download Plot')
)
)
) # close mainPanel