My First R Shiny App - shiny

Question

I've spent two days trying to create a Shiny app to no avail. It's fine just running the examples but when I want to modify it for my own preference, I just get constant errors and lack of functionality.
I have a simple dataset of 100 X observations and 100 Y observations. I want to plot histograms of both X and Y with slider inputs for bins. I also want to create a scatterplot of Y on X. I'd really appreciate some help here.
I'm not new to R but I'm new to Shiny. Is there a way I can use ggplot to create the visuals?
Many thanks.

Answer 1

This is a quick example with two different layouts. Use one of the ui.R of course. Put global.R in the same folder with ui.R and server.R
ui.R v1
library(shiny)
library(ggplot2)
shinyUI(fluidPage(
titlePanel("Quick Shiny Example"),
sidebarLayout(
sidebarPanel(
sliderInput("xBins",
"Number of bins for X variable:",
min = 1,
max = 50,
value = 30),
sliderInput("yBins",
"Number of bins for Y variable:",
min = 1,
max = 50,
value = 30)
),
mainPanel(
plotOutput("xDistPlot"),
plotOutput("yDistPlot"),
plotOutput("xyScatterPlot")
)
)
))
ui.R v2
library(shiny)
library(ggplot2)
shinyUI(fluidPage(
titlePanel("Quick Shiny Example"),
fluidRow(
column(width = 4,
sliderInput("xBins",
"Number of bins for X variable:",
min = 1,
max = 50,
value = 30)
),
column(width = 4,
sliderInput("yBins",
"Number of bins for Y variable:",
min = 1,
max = 50,
value = 30)
),
column(width = 4)
),
fluidRow(
column(width = 4,
plotOutput("xDistPlot")
),
column(width = 4,
plotOutput("yDistPlot")
),
column(width = 4,
plotOutput("xyScatterPlot")
)
)
))
server.R
library(shiny)
library(ggplot2)
shinyServer(function(input, output) {
output$xDistPlot <- renderPlot({
g <- ggplot(df, aes(x = x))
g <- g + geom_histogram(bins = input$xBins)
g
})
output$yDistPlot <- renderPlot({
g <- ggplot(df, aes(x = y))
g <- g + geom_histogram(bins = input$yBins)
g
})
output$xyScatterPlot <- renderPlot({
g <- ggplot(df, aes(x = x, y = y))
g <- g + geom_point()
g
})
})
global.R
df <- data.frame(
x = rnorm(100),
y = rnorm(100)*2
)

Answer 2

Here is my answer, with random numbers for X and Y, just as a quick idea. Adding ggplot to this should be easy.
library(shiny)
ui <- shinyUI(
fluidPage(
sliderInput("nrBinsX", "Number of bins to display for X", min = 2, max = 10, value = 5),
plotOutput("histX"),
sliderInput("nrBinsY", "Number of bins to display for Y", min = 2, max = 10, value = 5),
plotOutput("histY"),
plotOutput("scatterXY")
)
)
server <- shinyServer(function(input, output, session) {
dataFrame <- data.frame (
"X" = sample(100,100,replace = T),
"Y" = sample(100,100,replace = T)
)
getHist <- function (var,nr){
return (hist(
x = var,
breaks = seq(0,100,100/nr),
freq = T
) )
}
output$histX <- renderPlot({
return(
getHist( var = dataFrame$X,
nr = input$nrBinsX
) ) })
output$histY <- renderPlot({
return( return(
getHist( var = dataFrame$Y,
nr = input$nrBinsY
)
) ) })
output$scatterXY <- renderPlot({
return(
plot(x = dataFrame$X,
y = dataFrame$Y)
)
})
})
shinyApp(ui = ui, server = server)