How to hover over ggplot with transformed values in shiny - r

Question

I want to display some of the data in tooltip when hovering on the plot in shiny. I have used this script, and the data is showing nicely when I use the variables as they are (p and min_p). However what I really need is to display a log-transformed p and min_p, so my ggplot would be the following:
ggplot(dataset, aes(x = -log10(p), y = -log10(min_p))) +
geom_point()
And that's the problem, because hover_info does not recognize the data anymore, and I get the following error:
Error: replacement table has 0 rows, replaced table has 20
I am not sure how this can be fixed, and I admit I don't fully understand how the hovering works.
Here is the code with a sample data:
library(shiny)
library(shinydashboard)
library(ggplot2)
sidebar <- dashboardSidebar(
sidebarMenu(
menuItem("Plot result", tabName = "scatterplot", icon = icon("area-chart"))
))
body <- dashboardBody(
tabItems(
tabItem(tabName = "scatterplot",
fluidRow(
box(
uiOutput("scatterPlotButton"),
width = 5
),
box(
title="PLOT",solidHeader = TRUE, status="primary",
plotOutput("plot",
hover = hoverOpts("plot_hover", delay = 100, delayType = "debounce")),
uiOutput("hover_info"),
width=9
)
)
)
)
)
ui=dashboardPage(
dashboardHeader(title = "analysis"),
sidebar,
body
)
server=shinyServer(function(input, output, session) {
dataset <- structure(list(p = c(6.03934743495282e-02, 1.50433174696588e-01,
2.08047037184403e-03, 5.89297106629446e-05, 0.000102485231497565,
0.0010651774924444, 0.0126458836222225, 0.000210364148948929,
0.00274720409905674, 0.281095738489031, 0.000316170681574214,
0.0316321461125659, 0.000369171267912158, 0.000369171267912158,
0.0395213746526263, 0.475174078010843, 0.000718770258398781,
0.760859052164441, 0.000810153915789446, 0.000875314011490406),
ratio_p_group_min = c(1.57380553778931, 1.11245772000324,
1.504084996599, 1.00963266560562, 1.28098052443163, 1.49882201127675,
1.10761702001084, 0.767267328293303, 1.03412495601202, 1.33508933929913,
0.835478202626155, 0.998537147454481, 1.2008830437325, 1.2008830437325,
1.15710746065582, 0.99677375722945, 1.37744067975694, 1.3666109673056,
1.34583027836758, 1.34766012381264),
min_p = c(0.15789, 0.25772, 0.56599, 0.99632, 0.00004, 0.00275, 0.10761,
0.76726, 0.00103, 0.00013, 0.83547, 0.99853, 0.00120, 0.12008,
0.01157, 0.99677, 0.01377, 0.13666, 0.14583, 0.01347),
genes = c("Gene1", "Gene2", "Gene3", "Gene4", "Gene5", "Gene6", "Gene7",
"Gene8", "Gene9", "Gene10", "Gene11", "Gene12", "Gene13", "Gene14",
"Gene15", "Gene16", "Gene17", "Gene18", "Gene19", "Gene20")),
.Names = c("p", "ratio_p_group_min","min_p","genes"),
row.names = c(NA, 20L), class = "data.frame")
output$scatterPlotButton <- renderUI({
actionButton("scatterPlotButton", "Generate Plot", class="btn-block btn-primary")
})
scatterPlot <- eventReactive(input$scatterPlotButton,{
if (is.null(input$scatterPlotButton)) return()
dataset <- dataset[which(round(dataset$ratio_p_group_min,digits=2)>=0 & round(-log10(dataset$p),digits=2)>=0 & !is.na(dataset$ratio_p_group_min)),]
dataset$ratio_p_group_min=ifelse(dataset$ratio_p_group_min>2 & dataset$p>0.05,1,dataset$ratio_p_group_min)
ggplot(dataset, aes(x = -log10(p), y = -log10(min_p))) +
geom_point()
})
output$plot <- renderPlot({ scatterPlot() })
output$hover_info <- renderUI({
if (is.null(input$scatterPlotButton)) return()
dataset <- dataset[which(round(dataset$ratio_p_group_min,digits=2)>=0 & round(-log10(dataset$p),digits=2)>=0 & !is.na(dataset$ratio_p_group_min)),]
hover <- input$plot_hover
point <- nearPoints(dataset, hover, threshold = 5, maxpoints = 1, addDist = TRUE)
if (nrow(point) == 0) return(NULL)
left_pct <- (hover$x - hover$domain$left) / (hover$domain$right - hover$domain$left)
top_pct <- (hover$domain$top - hover$y) / (hover$domain$top - hover$domain$bottom)
left_px <- hover$range$left + left_pct * (hover$range$right - hover$range$left)
top_px <- hover$range$top + top_pct * (hover$range$bottom - hover$range$top)
style <- paste0("position:absolute; z-index:100; background-color: rgba(245, 245, 245, 0.85); ",
"left:", left_px + 2, "px; top:", top_px + 2, "px;")
wellPanel(
style = style,
p(HTML(paste0(point)))
)
})
})
shinyApp(ui=ui, server=server)
UPDATE
I have found a not so elegant solution: create new variables in dataset for -log10(p) and -log10(min_p) and use these new variables in ggplot.
dataset$LogP = -log10(dataset$p)
dataset$LogMinP = -log10(dataset$min_p)
ggplot(dataset, aes(x = LogP, y = LogMinP)) +
geom_point()
But I am still wondering if this could have been avoided somehow.

Answer 1

You could also use the plotly package. Simply call ggploty() after your ggplot object.