下面是我的代码。它可能看起来有点长，但实际上它是一个非常简单的应用程序。
用户应该上传一个很小的数据框（如果您在美国，则为 x.csv，如果您在欧洲，则为 x_Europe.csv）。然后用户应该点击按钮开始计算。最后，用户应该能够将这些计算的结果下载为数据框。
我的问题：上传文件后，当我单击“do_it”操作按钮时 - 没有任何反应。我可以看到它，因为我的控制台没有打印任何内容。为什么？毕竟，我的函数“main_calc”应该是 input$do_it 的 eventReactive？为什么 main_calc 中的所有计算仅在用户尝试下载结果后才开始发生？
重要提示：将“数据”函数与 main_calc 分开对我来说很重要。
非常感谢！
首先，在您的工作目录中生成以下 2 个文件之一：
# generate file 'x.csv' to read in later in the app:
write.csv(data.frame(a = 1:4, b = 2:5), "x.csv", row.names = F) # US file
write.csv2(data.frame(a = 1:4, b = 2:5), "x_Europe.csv", row.names = F)
这是闪亮应用程序的代码：
library(shiny)
ui <- fluidPage(
# User should upload file x here:
fileInput("file_x", label = h5("Upload file 'x.csv'!")),
br(),
actionButton("do_it", "Click Here First:"),
br(),
br(),
textInput("user_filename","Save your file as:", value = "My file x"),
downloadButton('file_down',"Save the output File:")
)
server <- function(input, output, session) {
#----------------------------------------------------------------------
# Function to read in either European (csv2) or American (csv) input:
#----------------------------------------------------------------------
ReadFile <- function(pathtofile, withheader = TRUE){
test <- readLines(pathtofile, n = 1)
if (length(strsplit(test, split = ";")[[1]]) > 1) {
print("Reading European CSV file")
outlist <- list(myinput = read.csv2(pathtofile, header = TRUE),
europe.file = 1)
} else {
print("Reading US CSV file")
outlist <- list(myinput = read.csv(pathtofile, header = TRUE),
europe.file = 0)
}
return(outlist)
}
#----------------------------------------------------------------------
# Data-related - getting the input file
#----------------------------------------------------------------------
Data <- reactive({
print("Starting reactive function 'Data'")
# Input file:
infile_x <- input$file_x
myx <- ReadFile(infile_x$datapath)$myinput
# European file?
europe <- ReadFile(infile_x$datapath)$europe.file
print("Finishing reactive function 'Data'")
return(list(data = myx, europe = europe))
})
#----------------------------------------------------------------------
# Main function that should read in the input and 'calculate' stuff
# after the users clicks on the button 'do_it' - takes about 20 sec
#----------------------------------------------------------------------
main_calc <- eventReactive(input$do_it, {
req(input$file_x)
# Reading in the input file:
x <- Data()$data
print("Done reading in the data inside main_calc")
# Running useless calculations - just to kill time:
myvector <- matrix(unlist(x), ncol = 1, nrow = 1000)
print("Starting calculations")
for (i in seq_len(10)) {
set.seed(12)
mymatr <- matrix(abs(rnorm(1000000)), nrow = 1000)
temp <- solve(mymatr) %*% myvector
}
print("Finished calculations")
# Creating a new file:
y <- temp
result = list(x = x, y = y)
print("End of eventReactive function main_calc.")
return(result)
}) # end of main_calc
#----------------------------------------------------------------------
# The user should be able to save the output of main_calc as a csv file
# using a string s/he specified for the file name:
#----------------------------------------------------------------------
output$file_down <- downloadHandler(
filename = function() {
paste0(input$user_filename, " ", Sys.Date(), ".csv")
},
content = function(file) {
print("Europe Flag is:")
print(Data()$europe)
if (Data()$europe == 1) {
x_out <- main_calc()$x
print("Dimensions of x in downloadHandler are:")
print(dim(x_out))
write.csv2(x_out,
file,
row.names = FALSE)
} else {
x_out <- main_calc()$x
print("Dimensions of x in downloadHandler are:")
print(dim(x_out))
write.csv(x_out,
file,
row.names = FALSE)
}
}
)
} # end of server code
shinyApp(ui, server)
以下是基于 MrFlick 的建议的解决方案：
# generate file 'x.csv' to read in later in the app:
# write.csv(data.frame(a = 1:4, b = 2:5), "x.csv", row.names = F)
# write.csv2(data.frame(a = 1:4, b = 2:5), "x_Europe.csv", row.names = F)
library(shiny)
library(shinyjs)
ui <- fluidPage(
# User should upload file x here:
fileInput("file_x", label = h5("Upload file 'x.csv'!")),
br(),
actionButton("do_it", "Click Here First:"),
br(),
br(),
textInput("user_filename","Save your file as:", value = "My file x"),
downloadButton('file_down',"Save the output File:")
)
server <- function(input, output, session) {
#----------------------------------------------------------------------
# Function to read in either European (csv2) or American (csv) input:
#----------------------------------------------------------------------
ReadFile <- function(pathtofile, withheader = TRUE){
test <- readLines(pathtofile, n = 1)
if (length(strsplit(test, split = ";")[[1]]) > 1) {
print("Reading European CSV file")
outlist <- list(myinput = read.csv2(pathtofile, header = TRUE),
europe.file = 1)
} else {
print("Reading US CSV file")
outlist <- list(myinput = read.csv(pathtofile, header = TRUE),
europe.file = 0)
}
return(outlist)
}
#----------------------------------------------------------------------
# Data-related - getting the input file
#----------------------------------------------------------------------
Data <- reactive({
print("Starting reactive function Data")
# Input file:
infile_x <- input$file_x
myx <- ReadFile(infile_x$datapath)$myinput
# European file?
europe <- ReadFile(infile_x$datapath)$europe.file
print("Finishing reactive function 'Data'")
return(list(data = myx, europe = europe))
})
#----------------------------------------------------------------------
# Main function that should read in the input and 'calculate' stuff
# after the users clicks on the button 'do_it' - takes about 20 sec
#----------------------------------------------------------------------
# Creating reactive Values:
forout_reactive <- reactiveValues()
observeEvent(input$do_it, {
print("STARTING observeEvent")
req(input$file_x)
# Reading in the input file:
x <- Data()$data
print("Done reading in the data inside observeEvent")
# Running useless calculations - just to kill time:
myvector <- matrix(unlist(x), ncol = 1, nrow = 1000)
print("Starting calculations")
for (i in seq_len(10)) {
set.seed(12)
mymatr <- matrix(abs(rnorm(1000000)), nrow = 1000)
temp <- solve(mymatr) %*% myvector
} # takes about 22 sec on a laptop
print("Finished calculations")
# Creating a new file:
y <- temp
forout_reactive$x = x
forout_reactive$y = y
print("End of observeEvent")
}) # end of main_calc
#----------------------------------------------------------------------
# The user should be able to save the output of main_calc as a csv file
# using a string s/he specified for the file name:
#----------------------------------------------------------------------
output$file_down <- downloadHandler(
filename = function() {
paste0(input$user_filename, " ", Sys.Date(), ".csv")
},
content = function(file) {
print("Europe Flag is:")
print(Data()$europe)
if (Data()$europe == 1) {
y_out <- forout_reactive$y
print("Dimensions of y in downloadHandler are:")
print(dim(y_out))
write.csv2(y_out,
file,
row.names = FALSE)
} else {
y_out <- forout_reactive$y
print("Dimensions of y in downloadHandler are:")
print(dim(y_out))
write.csv(y_out,
file,
row.names = FALSE)
}
}
)
} # end of server code
shinyApp(ui, server)
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