can we observe output from rendertable in shiny - r

Question

I have a application that has a reative table(based on 2 selectInputs) and a graph. The data for graph is taken from reactive table.
So both graph and table is using the same data. So while constructing a graph, can I observe what the table is having.
Or should I read the same table again in the graph?
I mean should we call head(iris,n = as.numeric(input$rows)) again twice below?
Example,
library(shiny)
library(DT)
library(rAmCharts)
ui <- fluidPage(
selectInput("rows","Rows",c(1:150)),
dataTableOutput("input_table"),
amChartsOutput("barplot",width = 750, height = 500)
)
server <- function(input, output, session) {
output$input_table <- renderDataTable({
new_iris <- head(iris,n = as.numeric(input$rows))
datatable(new_iris)
})
output$barplot <- renderAmCharts({
new_iris1 <- head(iris,n = as.numeric(input$rows)) ## should i call this again???????? Cannot we use from rendertable?
new_iris1 <- new_iris1 %>% group_by(Species) %>% summarise(total = sum(Petal.Length))
pipeR::pipeline(
amBarplot(
x = "Species",
y = "total",
ylab = "X",
xlab = "Y",
data = new_iris1,
labelRotation = 90
),
setChartCursor()
)
})
}
shinyApp(ui, server)

Answer 1

You may want to put your data object in a reactive expression so you can see what is being rendered, like so, this way you can access data() later on in your app
library(shiny)
library(DT)
library(dplyr)
library(rAmCharts)
ui <- fluidPage(
selectInput("rows","Rows",c(1:150)),
dataTableOutput("input_table"),
amChartsOutput("barplot",width = 750, height = 500)
)
server <- function(input, output, session) {
data <- eventReactive(input$rows,{
head(iris,n = as.numeric(input$rows))
})
output$input_table <- renderDataTable({
datatable(data())
})
output$barplot <- renderAmCharts({
new_iris1 <- data()
new_iris1 <- new_iris1 %>% group_by(Species) %>% summarise(total = sum(Petal.Length))
pipeR::pipeline(
amBarplot(
x = "Species",
y = "total",
ylab = "X",
xlab = "Y",
data = new_iris1,
labelRotation = 90
),
setChartCursor()
)
})
}
shinyApp(ui, server)