Recomputing renderplot based on renderui user input in RShiny - r

Question

I'm a bit of an RShiny and R novice. I'm trying to program an RShiny application. It would initially graphs a scatterplot matrix using the first three variables of the dataset by default. The user could then choose their own variable selections from a complete list of variables. Once variables are chosen, the user would click and action button and the graph would be recomputed using the newly selected variables.
I'm using selectinput rather than checkboxinput to accommodate datasets with many variables. I'm using the iris dataset. The code below produces the initial graph and allows the user to select the variables. I just can't figure out how to make it recompute the matrix plot. How do I do this? Thanks!
library(shiny)
runApp(list(
ui = fluidPage(
cols = colnames(iris),
headerPanel('Grow Clusters'),
tabsetPanel(
tabPanel("Plot",
sidebarPanel(
# uiOutput("varselect"),
selectInput("choose_vars", "Select variables to plot",
choices=colnames(iris), selected=iris[1:3], multiple=T),
actionButton("submitButton", "Produce Matrix Plot!")
),
mainPanel(
plotOutput('pairsplot')
)
),
tabPanel("Summary")
,
tabPanel("Table")
)
),
server = function(input, output) {
selectedData <- reactive({
cols = colnames(iris)
selectInput("choose_vars", "Select variables to plot",
choices=cols, selected=cols[1:3], multiple=T)
})
output$pairsplot <- renderPlot({
pairs(iris[1:3], pch = 21)
})
output$varselect <- renderUI({
iris[input$choose_vars]
plotOutput("pairsplot")
})
}
)
)

Answer 1

I think what you are looking for is quo function as in the Chris Beely blog: https://chrisbeeley.net/?p=1116
If you want users to pass arguments and then turn that character vector into objects r can read you need to use quo(input$choose_vars) and then in the plot you need to add !! before that passing variable. Notice you need to load dplyr.
library(shiny)
library(dplyr)
runApp(list(
ui = fluidPage(
cols = colnames(iris),
headerPanel('Grow Clusters'),
tabsetPanel(
tabPanel("Plot",
sidebarPanel(
# uiOutput("varselect"),
selectInput("choose_vars", "Select variables to plot",
choices=colnames(iris), selected=iris[1:3], multiple=T),
actionButton("submitButton", "Produce Matrix Plot!")
),
mainPanel(
plotOutput('pairsplot')
)
),
tabPanel("Summary")
,
tabPanel("Table")
)
),
server = function(input, output) {
selectedData <- reactive({
cols <- colnames(iris)
selectInput("choose_vars", "Select variables to plot",
choices=cols, selected=cols[1:3], multiple=T)
})
output$pairsplot <- renderPlot({
if(is.null(input$choose_vars) || length(input$choose_vars)<2){
pairs(iris[1:3], pch = 21)
} else {
var <- quo(input$choose_vars)
pairs(iris %>% select(!!var), pch = 21)
}
})
output$varselect <- renderUI({
iris[input$choose_vars]
plotOutput("pairsplot")
})
}
)
)