Trouble using zoom on ggplot2 shiny - r

Question

I'm new here as a user but I have searched like crazy for a problem I have encountered while trying to create a data visualization app with shiny in Rstudio.
The thing is, I want to read a .csv, understand it's columns, select wich column I want as x and as y axis, plot them with the type of graph I have chosen and be able to zoom in in a secondary plot whenever I want.
I'm almost there, the thing is that the zoom with brush that I have tried to do is no working properly. It doesn't understand the values of the axis correctly, instead it works as if both axis where only from 0 to 1, and then zoom in the correct way but with the wrong xlim and ylim.
Here is my ui.R:
library(shiny)
library(ggplot2)
base = read.csv("TESTE.csv", sep = ";")
tipos <- c("Dispersão", "Histograma", "Boxplot", "Área")
shinyUI(fluidPage(
titlePanel("MGM"),
sidebarLayout(
sidebarPanel(
selectInput("selectedColX", "Select colum for X axis", choices = colnames(base), selected = colnames(base)[7]),
selectInput("selectedColY", "Select colum for Y axis", choices = colnames(base), selected = colnames(base)[4]),
selectInput("selectedColor", "Select colum for colour axis", choices = colnames(base), selected = colnames(base)[6]),
selectInput("seletedGraph", "Select type of graph", choices = tipos, selected = tipos[1])
),
fluidRow(
column(width = 12, class = "well",
h4("Left plot controls right plot"),
fluidRow(
column(width = 10,
plotOutput("Disp", height = 300,
brush = brushOpts(
id = "Disp_brush",
clip = TRUE,
resetOnNew = TRUE
)
)
),
column(width = 10,
plotOutput("DispZoom", height = 300)
)
)
)
)
# mainPanel(
#
# plotOutput("Hist"),
# plotOutput("Box"),
# plotOutput("Ar")
# )
)
))
And then my Server.R:
library(shiny)
library(ggplot2)
base = read.csv("TESTE.csv", sep = ";")
tipos <- c("Dispersão", "Histograma", "Boxplot", "Área")
shinyServer(function(input, output) {
output$Disp <- renderPlot({
validate(need(input$seletedGraph=="Dispersão", message=FALSE))
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis))
gg <- gg + geom_point()
plot(gg)
})
ranges2 <- reactiveValues(x = NULL, y = NULL)
output$DispZoom <- renderPlot({
validate(need(input$seletedGraph=="Dispersão", message=FALSE))
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis)) + geom_point() + coord_cartesian(xlim = ranges2$x, ylim = ranges2$y)
plot(gg)
})
output$Hist <- renderPlot({
validate(need(input$seletedGraph=="Histograma", message=FALSE))
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis))
gg <- gg + geom_histogram()
gg
})
output$Box <- renderPlot({
validate(need(input$seletedGraph=="Boxplot", message=FALSE))
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis))
gg <- gg + geom_boxplot()
gg
})
output$Ar <- renderPlot({
validate(need(input$seletedGraph=="Área", message=FALSE))
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis))
gg <- gg + geom_area()
gg
})
observe({
brush <- input$Disp_brush
if (!is.null(brush)) {
ranges2$x <- c(brush$xmin, brush$xmax)
ranges2$y <- c(brush$ymin, brush$ymax)
} else {
ranges2$x <- NULL
ranges2$y <- NULL
}
})
})
Just ignore the other plots that are not the geom_point. As soon as I get this one working the others should work just fine, I guess...
Thank you so much, I'm having such a pain trying to figure this out!
Some texts are in portuguese, but I think everything is understandable enough.

Answer 1

Your brushed points are on scale from 0 to 1 in the brushOpts because you print or plot your variable instead of just returning it.
1. Short desmonstration
This short app show the difference between the brushed points scales according to how it has been returned.
library(shiny)
ui <- fluidPage(
fluidRow(
column(6,
# My plot rendering with print or plot
h4("Plot with print or plot variable"),
plotOutput("plot1", height = 300, brush = brushOpts(id = "plot1_brush", clip = TRUE, resetOnNew = TRUE)),
p(),
# Brushed points
"Brushed points informations, scale from 0 to 1",
verbatimTextOutput("brush1")
),
column(6,
# My plot rendering without print or plot
h4("Plot with a return variable"),
plotOutput("plot2", height = 300, brush = brushOpts(id = "plot2_brush", clip = TRUE, resetOnNew = TRUE)),
p(),
# Brushed points
"Brushed points informations, scale according to x and y variables",
verbatimTextOutput("brush2")
)
)
)
server <- function(input, output) {
data <- iris
# Plot1 I render with print or plot
output$plot1 <- renderPlot({
gg <- ggplot(data, aes(x = Sepal.Length, y = Petal.Length, color = Species)) + geom_point()
plot(gg)
})
# Brush points from plot1
output$brush1 <- renderPrint({
input$plot1_brush
})
# Plot2 I render just returning the variable
output$plot2 <- renderPlot({
gg <- ggplot(data, aes(x = Sepal.Length, y = Petal.Length, color = Species)) + geom_point()
return(gg)
})
# Brush points from plot2
output$brush2 <- renderPrint({
input$plot2_brush
})
}
shinyApp(ui = ui, server = server)
2. Reproductible example from your question
Herebelow I made a reproductible example using the iris dataset.
Also, I changed some characters because of accents.
ui.R
library(shiny)
library(ggplot2)
shinyUI(fluidPage(
titlePanel("MGM"),
sidebarLayout(
sidebarPanel(
uiOutput("plots_parameters")
),
mainPanel(
fluidRow(
column(12,
h4("Plot without zoom"),
plotOutput("Disp", height = 300, brush = brushOpts(id = "Disp_brush", clip = TRUE, resetOnNew = TRUE))
)
),
fluidRow(
column(12,
h4("Zoomed plot"),
plotOutput("DispZoom", height = 300)
)
)
)
)
))
server.R
library(shiny)
library(ggplot2)
base = iris
shinyServer(function(input, output) {
output$plots_parameters <- renderUI({
tipos <- c("Dispersao", "Histograma", "Boxplot", "Área")
choices <- colnames(base)
div(
selectInput("selectedColX", "Select colum for X axis", choices = choices, selected = "Sepal.Length"),
selectInput("selectedColY", "Select colum for Y axis", choices = choices, selected = "Petal.Length"),
selectInput("selectedColor", "Select colum for colour axis", choices = choices, selected = "Species"),
selectInput("seletedGraph", "Select type of graph", choices = tipos, selected = "Dispersao")
)
})
output$Disp <- renderPlot({
req(input$seletedGraph == "Dispersao")
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis))
gg <- gg + geom_point()
# Return variable without print or plot
gg
})
ranges2 <- reactiveValues(x = NULL, y = NULL)
output$DispZoom <- renderPlot({
req(input$seletedGraph == "Dispersao")
y_axis <- input$selectedColY
x_axis <- input$selectedColX
color_axis <- input$selectedColor
gg <- ggplot(base, aes_string(x = x_axis, y = y_axis, color = color_axis)) + geom_point() +
coord_cartesian(xlim = ranges2$x, ylim = ranges2$y)
# Return variable without print or plot
gg
})
observe({
brush <- input$Disp_brush
if (!is.null(brush)) {
ranges2$x <- c(brush$xmin, brush$xmax)
ranges2$y <- c(brush$ymin, brush$ymax)
} else {
ranges2$x <- NULL
ranges2$y <- NULL
}
})
})