Renaming coulmns names of a reactive dataframe in Shiny - r

Question

I have an R dataframe with several columns and I'd like users to select one column to plot against time. However, when I try to run this code, I get an error message.
country <- reactive({
input$variable
})
date_start <- reactive({
input$dateRange[1]
})
date_end <- reactive({
input$dateRange[2]
})
new_data <- reactive({
data[which(data$location== country() & data$date >= date_start() & data$date<=date_end()),c("date","location",input$info)]
names(new_data()) <- c("date", "location", "col1")
})
The error is:
Error in names(new_data()) <- c("date", "location", "col1") :
invalid (NULL) left side of assignment
Can anyone help me with that, please?

Answer 1

This should do the trick:
new_data <- reactive({
data_selection <- data[which(data$location== country() & data$date >= date_start() & data$date<=date_end()),c("date","location",input$info)]
colnames(data_selection) <- c("date", "location", "col1")
data_selection
})
You were referencing the reactive value inside the reactive call, which is then assigned to the new_data. Because this happens before the assignment, the value of the new_data within the call is null. Fortunately there is no need to do that.
Note: as you didn't post your data, I had no way to actually test your code.
However here is a minimal working example to illustrate the concept:
library(shiny)
ui <- fluidPage(
dataTableOutput("geysers")
)
server <- function(input, output) {
test <- reactive({
a <- faithful[1:3,]
colnames(a) <- c("a", "b")
a
})
output$geysers <- renderDataTable({test()})
}
shinyApp(ui = ui, server = server)