Render different plots based on if/else on existence of reactive variable - r

Question

I'm trying to create an app that allows 1) a user to hover over scatter plot points, which displays a label associated with the point, and 2) search for a specific point by label.
Currently, to highlight a point, I re-plot the graph each time the user submits a search term, adding that single point on top of rest of the points that have been plotted.
In order to avoid the server re-plotting before the user finishes typing the label, I require that the "search" button be pressed. However, I'm struggling to get the plot to display BEFORE the user has searched for any labels.
Here's what I have so far:
library(shiny)
library(ggplot2)
library(ggiraph)
df <- data.frame(x = rnorm(100), y = rnorm(100), label = paste("gene", seq(100)))
head(df)
x y label
1 -0.3383215 0.91212341 gene 1
2 -0.5318215 -0.63273778 gene 2
3 1.1281345 -0.01296204 gene 3
4 -1.2964345 -2.21689946 gene 4
5 1.5877938 -0.24993362 gene 5
6 0.6385419 0.07849135 gene 6
gg_scatter <- ggplot(data = df, aes(x, y)) +
geom_point_interactive(aes(tooltip = label, data_id = label))
ui <- fluidPage(
textInput(inputId = "gene_symbol",
label = "Search for a gene",
placeholder = "gene 1"),
actionButton(inputId = "go",
label = "Search"),
girafeOutput("scatterplot"),
textOutput("message")
)
server <- function(input, output) {
gene_search <- eventReactive(input$go, {
input$gene_symbol
})
output$scatterplot <-
renderGirafe({
gg_scatter_highlight <- gg_scatter +
geom_point_interactive(data = subset(df, label == gene_search()),
tooltip = gene_search(),
size = 3,
color = "red")
girafe(code = print(gg_scatter_highlight),
options = list(opts_selection(type = "single")))
})
output$message <- renderText({
if(sum(is.element(df$label, req(gene_search()))) == 0) {
paste("Gene not found")
}
})
}
shinyApp(ui = ui, server = server)
I'm trying to add something like this to output$scatterplot:
output$scatterplot <-
renderGirafe({
## If the user has not searched for anything, plot without any points highlighted
if(!isTruthy(gene_search)) {
girafe(code = print(gg_scatter),
options = list(opts_selection(type = "single")))
}
## Highlight the point that the user searched for
else {
gg_scatter_highlight <- gg_scatter +
geom_point_interactive(data = subset(df, label == gene_search()),
tooltip = gene_search(),
size = 3,
color = "red")
girafe(code = print(gg_scatter_highlight),
options = list(opts_selection(type = "single")))
}
})
... Unfortunately this still results in no plot being displayed until a label is searched.
Any help would be much appreciated.

Answer 1

Set ignoreNULL = FALSE in eventReactive to have a default value at the beginning.
library(shiny)
library(ggplot2)
library(ggiraph)
gg_scatter <- ggplot(data = df, aes(x, y)) +
geom_point_interactive(aes(tooltip = label, data_id = label))
ui <- fluidPage(
textInput(inputId = "gene_symbol",
label = "Search for a gene",
placeholder = "gene 1"),
actionButton(inputId = "go",
label = "Search"),
girafeOutput("scatterplot"),
textOutput("message")
)
server <- function(input, output) {
gene_search <- eventReactive(input$go, {
input$gene_symbol
}, ignoreNULL = FALSE)
output$scatterplot <-
renderGirafe({
gg_scatter_highlight <- gg_scatter +
geom_point_interactive(data = subset(df, label == gene_search()),
tooltip = gene_search(),
size = 3,
color = "red")
girafe(code = print(gg_scatter_highlight),
options = list(opts_selection(type = "single")))
})
output$message <- renderText({
if(sum(is.element(df$label, req(gene_search()))) == 0) {
paste("Gene not found")
}
})
}
shinyApp(ui = ui, server = server)