How to Pass input$variable to renderPlotly in a flexadashboard

Question

newData() is a dynamic generated data frame by a reactive statement based on user inputs:

selectInput("year", "Year", c("2019", "2020", "2021"), selected = "2021")
selectInput("fruit", "Fruit", names(FruitSales$fname), selected = "Pineapple")

For year 2021, for example, newData() is:

        fruit  x2021_sales
1    Pineapple 42
2       Orange 36
3       Carrot 56
4        Onion 82
5      Avocado 94
6     Mushroom 24
7        Apple 23
8       Banana 46
9        Mango 61
10  Strawberry 43

Note the name of the second column. It is generated by concatenating "x", input$year, and "_sales".

I want to plot a treemap of newData() with plotly: labels = ~get(input$fruit), values = ~x20yy_sales. I've tried a couple of ways. The first is to use ggplot to generate a treemap and then ggplotly it. It didn't work because somehow geom_treemap_text wasn't compatible with plotly. The second is below:

renderPlotly({
    treeplot <- plot_ly(NewData(),
             labels = ~get(input$fruit),
             parents = ~NA,
             # values = ~x2021_sales, ## --> works
             # values = paste0("x", input$year, "_sales"), ## --> doesn't work
             # values = paste0("x", eval(as.name(input$year)), "_sales"), ## --> doesn't work
             type = "treemap"
                )
  treeplot
})

Without values, the dashboard worked and gave me a treemap with euqal-sized blocks as expected. If values = ~x2021_sales was hard-coded in, it also worked. but when I tried to pass input$year from the input sidebar to values, nothing worked. Anyone knows what to do?

Edit 1: x = as.formula(paste0("~",input$x)) suggested by the moderator returned errors, something to the effect of "invalid formula."

Edit 2: The trick of labels = ~get(input$fruit) was borrowed from here https://stackoverflow.com/questions/66337613/selective-y-variable-in-shiny-plotly-output and here https://stackoverflow.com/questions/63543144/how-to-make-a-plotly-chart-of-variables-selected-by-a-user-in-shiny-or-flexdahsb.

You still need the `get()` for the string value that you paste together. — MrFlick, Dec 20 '22 at 14:42
Can you elaborate a little on why ```get()``` is needed for ```paste0()```? Why ```paste0("x", get(input$year), "_sales")``` failed to work? — tcollar, Dec 20 '22 at 14:53
Because `paste()` returns a string. `plotly` needs the actual variable of values, not the name of the variable. `get()` returns the value for a variable with that name. You need to build the full name of the variable as a string, then then `get()` that value. Here `x` and `_sales` are part of the variable name so they need to be inside the `get()` — MrFlick, Dec 20 '22 at 15:53

score 1 · Answer 1 · answered Dec 20 '22 at 14:39

This works:

input <- list(fruit = "Species",
              year = "Length")
plotly::plot_ly(iris,
        labels = ~get(input$fruit),
        parents = ~NA,
        # values = ~x2021_sales, ## --> works
        values = ~get(paste0("Sepal.", input$year)), ## --> doesn't work
        # values = paste0("x", eval(as.name(input$year)), "_sales"), ## --> doesn't work
        type = "treemap"
)

So please try:

renderPlotly({
  treeplot <- plot_ly(NewData(),
                      labels = ~get(input$fruit),
                      parents = ~NA,
                      values = ~get(paste0("x", input$year, "_sales")), ## --> doesn't work
                      type = "treemap"
  )
  treeplot
})

It worked. In contrast, the solution suggested the moderator ```x = as.formula(paste0("~",input$x)),``` didn't solve my problem. I wonder why. Can you elaborate why ```get()``` worked? — tcollar, Dec 20 '22 at 14:49

How to Pass input$variable to renderPlotly in a flexadashboard

1 Answers1