Capturing instance of reactive values? - r

Question

In R Shiny, Is there a way of capturing a particular instance of reactive value so then that instance is totally unreactive?
So I'd have a table made up of reactive values and when the user hits the submit button those values are copied over to an un reactive table which I can then go on to manipulate etc.
So in the following code, the user enters their values into a table from rhandsontable package (which is awesome btw), and all I am trying to do is convert it to a basic data frame namely tabplot which should be unreactive so I can go ahead and do any type of operations on it.
library(shiny)
library(rhandsontable)
seq1 <- seq(1:6)
mat1 <- matrix(seq1, 2)
tabplot<-data.frame(car=numeric(2),num=numeric(2),truck=numeric(2))
did_recalc <- FALSE
ui <- fluidPage(
rHandsontableOutput('table'),
tableOutput('result'),
tableOutput('kl'),
textOutput('ca'),
actionButton("goButton","Confirm"),
actionButton("checkButton","Apply"),
br(),
actionButton("recalc", "Return to original values")
)
server <- function(input,output,session)({
tabplot<-data.frame(car=numeric(2),num=numeric(2),truck=numeric(2))
seq1 <- seq(1:6)
mat1 <- matrix(seq1, 2)
mat1<-data.frame(mat1)
#creates reactive values for the data frame
#obviously they have to be reactive values to function with the rhandsontable which is being continuously updated
#as the documentation says "values taken from the reactiveValues object are reactive but the object itself is not
values <- reactiveValues(data=mat1)
#if recalc --- which connects to an action button in the ui is hit, values goes back to original data frame
observe({
input$recalc
values$data<-mat1
})
#Where the magic happens
output$table <- renderRHandsontable({
rhandsontable(values$data,selectCallback = TRUE)
})
#this changes the handsontable format to an r object
observe({
if(!is.null(input$table))
values$data <-hot_to_r(input$table)
})
#Here we create a reactive function that creates a data frame of the rhandsontable output but it is a reactive function
fn<-reactive({
co<-data.frame((values$data))
return(co)
})
#Bit of testing, this demonstrates that the fn() is only updated after the button is pressed
output$result<-renderTable({
input$goButton
isolate({
fn()
})
})
isolate({
# tabplot<-reactive({ #Format co[desired row:length(colums)][desired column]
tabplot[1,1:3][1]<-fn()[1,1:3][1]
tabplot[1,1:3][2]<-fn()[1,1:3][2]
tabplot[1,1:3][3]<-fn()[1,1:3][3]
tabplot[2,1:3][1]<-fn()[2,1:3][1]
tabplot[2,1:3][2]<-fn()[2,1:3][2]
tabplot[2,1:3][3]<-fn()[2,1:3][3]
})
output$kl<-renderTable({
tabplot
})
observe({
input$goButton
output$ca<-renderText({
tabplot$car
cat('\nAccessing Subset with $:', tabplot$car)
cat('\nAccessing specific cell:',tabplot[1,3])
cat('\noperations on specific cell:',tabplot[1,3]*2)
})
})
})
shinyApp(ui = ui, server = server)

Answer 1

This might be what you want. It leverages the much scorned <<- operator, but it is what I do when I need to subvert the "lazy reactive" architecture of shiny.
Note I set a parallel dataframe tabplot1 and display it beneath where you display tabplot.
library(shiny)
library(rhandsontable)
seq1 <- seq(1:6)
mat1 <- matrix(seq1, 2)
tabplot<-data.frame(car=numeric(2),num=numeric(2),truck=numeric(2))
did_recalc <- FALSE
ui <- fluidPage(
rHandsontableOutput('table'),
tableOutput('result'),
tableOutput('kl'),
tableOutput('kl1'),
textOutput('ca'),
actionButton("goButton","Confirm"),
actionButton("checkButton","Apply"),
br(),
actionButton("recalc", "Return to original values")
)
server <- function(input,output,session)({
tabplot<-data.frame(car=numeric(2),num=numeric(2),truck=numeric(2))
tabplot1 <- tabplot
seq1 <- seq(1:6)
mat1 <- matrix(seq1, 2)
mat1<-data.frame(mat1)
#creates reactive values for the data frame
#obviously they have to be reactive values to function with the rhandsontable which is being continuously updated
#as the documentation says "values taken from the reactiveValues object are reactive but the object itself is not
values <- reactiveValues(data=mat1)
#if recalc --- which connects to an action button in the ui is hit, values goes back to original data frame
observe({
input$recalc
values$data<-mat1
})
#Where the magic happens
output$table <- renderRHandsontable({
rhandsontable(values$data,selectCallback = TRUE)
})
#this changes the handsontable format to an r object
observe({
if(!is.null(input$table))
values$data <-hot_to_r(input$table)
})
#Here we create a reactive function that creates a data frame of the rhandsontable output but it is a reactive function
fn<-reactive({
co<-data.frame((values$data))
return(co)
})
#Bit of testing, this demonstrates that the fn() is only updated after the button is pressed
output$result<-renderTable({
input$goButton
tabplot1 <<- data.frame(values$data)
colnames(tabplot1) <<- colnames(tabplot)
isolate({
fn()
})
})
isolate({
# tabplot<-reactive({ #Format co[desired row:length(colums)][desired column]
tabplot[1,1:3][1]<-fn()[1,1:3][1]
tabplot[1,1:3][2]<-fn()[1,1:3][2]
tabplot[1,1:3][3]<-fn()[1,1:3][3]
tabplot[2,1:3][1]<-fn()[2,1:3][1]
tabplot[2,1:3][2]<-fn()[2,1:3][2]
tabplot[2,1:3][3]<-fn()[2,1:3][3]
})
output$kl<-renderTable({
tabplot
})
output$kl1<-renderTable({
input$goButton
tabplot1
})
observe({
input$goButton
output$ca<-renderText({
tabplot$car
cat('\nAccessing Subset with $:', tabplot$car)
cat('\nAccessing specific cell:',tabplot[1,3])
cat('\noperations on specific cell:',tabplot[1,3]*2)
})
})
})
shinyApp(ui = ui, server = server)
Yielding: