Update data value to NA based from a specific column based for the data points that are under the brush - Demo - brushedPoints() in R Shiny

app.R

# Load required packages
library(shiny)
library(ggplot2)

# UI Code begins here
ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      ## Add inputs widgets later
    ),
    
    # Outputs
    mainPanel(
      plotOutput(outputId = "scatterplot2", brush = "plot_brush"), # the scatter plot
      tableOutput("table") # dataset

      
    )
  )
)

# Server code begins here
server <- function(input, output) {
  
  
  mt <- reactiveValues(data=head(mtcars,10)) # making the dataset reactiveValues so that any changes in data later could be reflected throughout
  
  
  # Create scatterplot object the plotOutput function is expecting
  output$scatterplot2 <- renderPlot({
    ggplot(data = mt$data, aes(x = mpg, y = hp)) +
      geom_point()
  })
  
  ## Returns the dataset
  output$table <- renderTable({
    mt$data
  })
  
 
  
  # Observe will listen for brush over the point and change the "hp" column values for all data points under brush to NA
  observe({
    df = brushedPoints(mt$data, brush = input$plot_brush, allRows = TRUE)
    index = which(df$selected_== TRUE)
    df[index, "hp"] = NA
    df = df[, -which(names(df) %in% "selected_")]
    mt$data = df
    
  })
  
  }

# Create a Shiny app object
shinyApp(ui = ui, server = server)