Styjun

I'm using shiny to create a list of reactive data.frames that I want to pass into a function. The function works well with lists of non-reactive data.frames, but I cannot figure out how to either 1) isolate the list of reactive data.frames just before passing it into the function, or 2) pass it into the function and then isolate the data.frames inside the function. The output of this function will be downloaded from shiny app, not rendered to output.

non_reactive_df_list <- isolate(df_list()) #throws error because the list isn't reactive, just the dataframes (df_list[[i]]) are reactive

non_reactive_df_list <- map(df_list, isolate) #doesn't work, and even it if did, there is no trigger/actionButton

What I really want would be like ..

df_list <- eventIsolateListElements(input$actionButton, df_list) # where df_list contains reactive elements

I don't know how many dfs there will be in the list.

The function I'm using:

dfList2string <- function(dbList) 
 string <- "**DataFrame String**"
 for (i in seq_along(dbList)) 
 string <- paste(string, names(dbList[i]), sep = 'nn')
 sub_string <- paste(names(dbList[[i]]), collapse = ', ')
 string <- paste(string, sub_string, sep = 'n')
 for (j in seq(1:nrow(dbList[[i]]))) 
 sub_string <- paste(dbList[[i]][j,], collapse = ', ' )
 string <- paste(string, sub_string, sep = 'n')
 
 
 return(string)

if you want a shiny app example, I made a small shiny app that describes what I want. I do not include the code that doesn't work because it just crashes (makes troubleshooting difficult)

 require(shiny)

#make list of two non-reactive dataframes
dfList <- list()
dfList$df1 <- data.frame(a = rnorm(5, 1),
 b = rnorm(5, 1))
dfList$df2 <- data.frame(a = rnorm(5, 3),
 b = rnorm(5, 3))

ui <- fluidPage(

 fluidRow(
 HTML('<h3>User Inputs</h3>'),
 numericInput('dfmean1', 'select mean df1', value= 1), #user choose mean for df1
 numericInput('dfmean2', 'select mean df2', value= 2), #user choose mean for df2
 HTML('<h3>Reactive df1</h3>'),
 tableOutput('reactive_table1'), #show reactive df1 table for clarity
 HTML('<h3>Reactive df2</h3>'),
 tableOutput('reactive_table2'), #show reactive df2 table for clarity
 HTML('<h3>Button to trigger Isolation of reactive list of df1 and df2</h3>'),
 actionButton('action', 'WriteToText'), #this button should trigger the conversion of reactive_dfList to text string
 HTML('<h3>Example function output using normal list of non-reactive dfs </h3>'),
 verbatimTextOutput('text_table') #this shows output of a function that converts non-reactive dfList to text string
 )
)

server <- function(session, input, output) 

 #make list of two reactive dataframes
 reactive_dfList <- list() #initiate list to contain the two reactive dfs 1 and 2

 reactive_dfList$df1 <- reactive(
 data.frame(a = rnorm(5, input$dfmean1),
 b = rnorm(5, input$dfmean1))
 )

 reactive_dfList$df2 <- reactive(
 data.frame(a = rnorm(5, input$dfmean2),
 b = rnorm(5, input$dfmean2))
 ) 

 #view the tables of reactive dataframs for clarity
output$reactive_table1 <- renderTable( reactive_dfList$df1() )
output$reactive_table2 <- renderTable( reactive_dfList$df2() )

#function that converts list of dfs to a text string
dfList2string <- function(dbList) 
 string <- "**DataFrame String**"
 for (i in seq_along(dbList)) 
 string <- paste(string, names(dbList[i]), sep = 'nn')
 sub_string <- paste(names(dbList[[i]]), collapse = ', ')
 string <- paste(string, sub_string, sep = 'n')
 for (j in seq(1:nrow(dbList[[i]]))) 
 sub_string <- paste(dbList[[i]][j,], collapse = ', ' )
 string <- paste(string, sub_string, sep = 'n')
 
 
 return(string)


output$text_table <- renderText(
 dfList2string(dfList)
)



shinyApp(ui, server)