shiny app with own function - r

Question

I want to implement a function in a Shiny app. My own function get_calculate() has the arguments data and tolerance as input and retruns a list with a data.frame and a plot.
I want to show the output depending on tolerance. In my server function I use reactive() to run get_calculate() but it doesn't work.
If I write in renderPlot() and renderDataTable() get_calculate() works.
For large datasets, however, it's inefficient because Shiny will have to run get_calculate() twice.
library(shiny)
library(shinydashboard)
library(foreign)
#load my own function
source("01-get_calculate.R")
ui <- dashboardPage(
dashboardHeader(title = "Analysis"),
dashboardSidebar(
sidebarMenu(
menuItem("Load data", tabName = "data", icon = icon("database")),
menuItem("Mainboard", tabName = "Mainboard", icon = icon("dashboard"))
)
),
dashboardBody(
tabItems(
tabItem(tabName = "data",
fileInput("datafile", "Choose file",
accept = c("text/csv/rds/dbf", 'text/comma-separated-values,text/plain')),
dataTableOutput("mytable")
),
tabItem(tabName = "Mainboard",
fluidRow(
box(
title = "Input", status = "primary", solidHeader = TRUE, collapsible = TRUE,
sliderInput(inputId = "tol",
label = "Tolerance",
value = 4, min = 1, max = 15, step = 1)
)),
fluidRow(
box(
title = "Adherence Curve", status = "warning", solidHeader = TRUE, collapsible = TRUE,
plotOutput("plot_kpm")
),
box(
title = "Overview Table", status = "primary", solidHeader = TRUE, collapsible = TRUE,
tableOutput("table_kpm")
)
)
)
)
)
)
server <- function(input, output) {
filedata <- reactive({
infile <- input$datafile
if (is.null(infile)) {
return(NULL)
}
read.dbf(infile$datapath)
})
output$mytable <- renderDataTable({
filedata()
})
**test <- reactive({
get_calculate(filedata(), tolerance = input$tol)
})
output$plot_kpm <- renderPlot({
test$kpm_chart
})
output$table_kpm <- renderDataTable({
test$data_kpm[, c("Time", "numbers", "Percent")]
})**
}
shinyApp(ui = ui, server = server)

Answer 1

The error you mentioned is most likely from renderDataTable where you are trying to pick couple of columns from test$data_kpm. Check the dataframe for exact column names.

Answer 2

This version of my shiny app runs. But it' ineffcient because shiny have to runs get_calculate twice.
server <- function(input, output) {
#This function is repsonsible for loading in the selected file
filedata <- reactive({
infile <- input$datafile
if (is.null(infile)) {
# User has not uploaded a file yet
return(NULL)
}
read.dbf(infile$datapath)
})
output$mytable <- renderDataTable({
filedata()
})
output$plot_kpm <- renderPlot({
get_calculate(filedata(), tolerance = input$tol)$kpm_chart
})
output$table_kpm <- renderTable({
get_calculate(filedata(), tolerance = input$tol)$data_kpm[, c("Time", "Percent", "Patients")]
})
output$download_mainboard_adherence_table <- downloadHandler(
filename = paste("adherence_table", '.csv', sep=''),
content = function(file) {
write.csv(get_calculate(filedata(), tolerance = input$tol)$data_kpm[, c("Time", "Percent", "Patients")], file)
}
)
}

Answer 3

Why don't you use a reactive expression to run your get_calculate just once ? And then use the result in your output$plot_kpm and output$table_kpm ?
This will optimize your code.