Saving data frame of user input - r

Question

Note: Please feel free to criticize the code I have written as I'm learning, what I did wrong, how I can improve etc.
I am learning R and shiny and would like to implement a calculation using the users input, however I am having difficulty storing the user input into a data frame for me to access to run a calculation later.
My idea is to get the user to define a probability distribution for his or her selected variables from the iris dataset. Once he defines them I want to store those defined variables into a data frame so that I can run a calculation such as a Monte Carlo etc. using the users defined data frame later on (so I would need to call upon that as a data frame).
I have tried to make the code as simple as possible below :
library(shiny)
ui <- fluidPage(
fluidRow(
column(4,
wellPanel(
selectizeInput(inputId= "invar", label= "Select Variable",
choices= names(iris),
selected= names(iris)[1],
multiple=T),
uiOutput("moC"))),
mainPanel(
tableOutput("tab")
)
))
server <- function(input, output) {
sorted <- reactive({
data <- iris[ ,c(input$invar)]
data})
output$moC <- renderUI({
numvar<- length(input$invar)
lapply(1:numvar, function(i) {
tagList(
selectInput("inv",paste0("Please Select Probability Distribution of ", input$invar[i]),
choices = c("Normal","Uniform")),
conditionalPanel(condition = "input.inv=='Normal'",
textInput("invarpdfmean","Please Select Input Variable Mean:",0.25),
textInput("invarpdfsd","Please Select Input Variable Standard Deviation", 0.02)),
conditionalPanel(condition = "input.inv=='Uniform'",
textInput("invarpdfmin","Please Select Minimum Input Variable Value:",0.18),
textInput("invarpdfmax","Please Select Maximum Input Variable Value", 0.3))
)})})
}
EDIT: Updated code as per comments. Thanks
library(shiny)
ui <- fluidPage(
fluidRow(
column(4,
wellPanel(
selectizeInput(inputId= "invar", label= "Select Variable",
choices= names(iris),
selected= names(iris)[1],
multiple=TRUE),
uiOutput("moC"))),
mainPanel(
tableOutput("tab")
)
))
server <- function(input, output) {
sorted <- reactive({
iris[input$invar]
})
output$moC <- renderUI({
numvar<- length(input$invar)
lapply(1:numvar, function(i) {
tagList(
selectInput("inv",paste0("Please Select Probability Distribution of ", input$invar[i]),
choices = c("Normal","Uniform")),
conditionalPanel(condition = "input.inv=='Normal'",
textInput("invarpdfmean","Please Select Input Variable Mean:",0.25),
textInput("invarpdfsd","Please Select Input Variable Standard Deviation", 0.02)),
conditionalPanel(condition = "input.inv=='Uniform'",
textInput("invarpdfmin","Please Select Minimum Input Variable Value:",0.18),
textInput("invarpdfmax","Please Select Maximum Input Variable Value", 0.3))
)})})
}
shinyApp(ui, server)
EDIT 2:
Seems I wasn't clear apologize:
The desired output is a histogram of a linear model of the users selected variables with the data coming from the users defined variables. So if he selects Sepal.Length and Petal.Length and defines them with a uniform or normal distribution I want to run a Monte Carlo on the linear model using a data frame created from the users input.
So later on i want to run a code that looks something like this:
n<-1000
Lm <- Sepal.Length + Petal.Length
for (n in 1:n) {
H=predict(LM,MCtab)
}
where MCtab would be a data frame which is created by the user using the variables he or she selects. This is what I have not been able to figure out how to do.

Answer 1

For MCtab (which is just a subset of your dataset based on user selected inputs), you can use MCtab <- iris[ , input$invar]. Note the comma there. Also, you should check if input$invar is empty in case user has deleted all the choices.