Finding the random x-values used by geom_jitter - r

Question

I want to be able to select observations from a box plot with jittered points over top. I have been somewhat successful by having the point click find the category, look at the y-value and select the observation. The following code shows my progress so far:
# ------------------------------Load Libraries---------------------------------
library(shiny)
library(ggplot2)
library(dplyr)
# -------------------------Print Boxplot to Screen-----------------------------
ui <- fluidPage(plotOutput('irisPlot', click = 'irisClick'))
server <- function(input, output){
# --------------------------Store Clicked Points-------------------------------
clicked <- reactiveValues(rows = rep(TRUE,nrow(iris)))
# ---------------------------Modify the Dataset--------------------------------
IRIS <- reactive({iris %>% mutate(index = clicked$rows)})
# ---------------------Select Points Through Plot Click------------------------
observeEvent(
input$irisClick,{
nS <- iris %>% mutate(selected = rep(FALSE,nrow(iris)))
lvls <- levels(iris$Species)
plant <- lvls[round(input$irisClick$x)]
pxl <- which(
sqrt((iris$Sepal.Width-input$irisClick$y)^2) %in%
min(sqrt((iris$Sepal.Width-input$irisClick$y)^2))
)
point <- iris[pxl,'Sepal.Width']
nS[nS$Species == plant & nS$Sepal.Width %in% point,'selected'] <- TRUE
clicked$rows <- xor(clicked$rows, nS$selected)
})
# --------------------------Generate the Boxplot-------------------------------
output$irisPlot <- renderPlot({
set.seed(1)
ggplot(IRIS(), aes(x = Species, y = Sepal.Width))+
geom_boxplot(na.rm = TRUE,outlier.shape = NA)+
geom_jitter(
na.rm = TRUE,
width = .8,
aes(shape = index, size = index, colour = index)
)+
theme(
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.background = element_blank(),
panel.border = element_rect(colour = 'black', fill = NA),
legend.position = "none"
)+
scale_shape_manual(values = c('FALSE'= 1,'TRUE'= 19))+
scale_size_manual(values = c('FALSE' = 4, 'TRUE'= 2))+
scale_colour_manual(values = c('TRUE' = "#428BCA", 'FALSE' = '#FAA634'))
})
}
shinyApp(ui, server)
As I said the code mostly works but it can be inconsistent. Sometimes it can't find a point, other times it selects a large group of points or selects a point on the opposite side of the box plot. I figure the best way to solve this is to have both an x and y coordinate to select the point however, since the x values are randomly generated I need geom_jitter() to tell me what x-values it is using for a given plot but I have not been able to find any way to access this. Any help finding this information would be greatly appreciated.

Answer 1

My thanks to aosmith for telling me about the layer_data() function and to Peter Ellis for suggesting that I use geom_point() instead of geom_jitter() both comments were instrumental in helping me solve my problem.
What I had to do was create a new plot object in the global environment to jitter the points. Then use the layer_data() function to return the newly created x-values.
Finally, using those x-values, I created a new plot object and layered the points over top using geom_point(). Here is the completed code for anyone interested.
# ------------------------------Load Libraries---------------------------------
library(shiny)
library(ggplot2)
library(dplyr)
# ----------------------------Generate X Coords--------------------------------
set.seed(1)
g1 <- ggplot(iris, aes(x = Species, y = Sepal.Width))+
geom_boxplot(na.rm = TRUE,outlier.shape = NA)+
geom_jitter(na.rm = TRUE,width = .8)
xPoints <- layer_data(g1, i = 2)$x
# -------------------------Print Boxplot to Screen-----------------------------
ui <- fluidPage(
plotOutput('irisPlot', click = 'irisClick')
)
server <- function(input, output){
# --------------------------Store Clicked Points-------------------------------
clicked <- reactiveValues(rows = rep(TRUE,nrow(iris)))
rand <- reactiveValues(x = rep(NA,nrow(iris)))
# ---------------------------Modify the Dataset--------------------------------
IRIS <- reactive({iris %>% mutate(index = clicked$rows)})
# ---------------------Select Points Through Plot Click------------------------
observeEvent(
input$irisClick,{
nS <-data.frame( iris, x = xPoints)
point <- nearPoints(
df = nS,
coordinfo = input$irisClick,
xvar = 'x',
yvar = 'Sepal.Width',
allRows = TRUE
)
clicked$rows <- xor(clicked$rows, point$selected_)
})
# --------------------------Generate the Boxplot-------------------------------
output$irisPlot <- renderPlot({
ggplot(IRIS(), aes(x = Species, y = Sepal.Width))+
geom_boxplot(na.rm = TRUE,outlier.shape = NA)+
geom_point(
aes(
x = xPoints,
y = iris$Sepal.Width,
shape = index,
size = index,
colour = index
),
inherit.aes = FALSE
)+
theme(
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.background = element_blank(),
panel.border = element_rect(colour = 'black', fill = NA),
legend.position = "none"
)+
scale_shape_manual(values = c('FALSE'= 1,'TRUE'= 19))+
scale_size_manual(values = c('FALSE' = 4, 'TRUE'= 2))+
scale_colour_manual(values = c('TRUE' = "#428BCA", 'FALSE' = '#FAA634'))
})
output$x <- renderPlot({
})
}
shinyApp(ui, server)

Answer 2

Just for the benefit of people like me who might be googling this problem I solved it very easily using Peter Ellis's suggestion of jittering the points myself using jitter().
I'm making it into an answer because I thought it should be more visible, I nearly missed it when I was looking at this page.