Create a ShinyApp to draw scatterplots using ggplot - r

Question

I want to create a shiny app to draw scatterplots by selecting the variables in the uploaded data set to shiny app. I want to create plots using ggplot and plotly. The code I tried is as follow. But my app does not give the plot.
library(shiny)
library(datasets)
library(plotly)
ui <- shinyUI(fluidPage(
titlePanel("Column Plot"),
tabsetPanel(
tabPanel("Upload File",
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('file1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv')),
tags$br(),
checkboxInput('header', 'Header', TRUE),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
','),
radioButtons('quote', 'Quote',
c(None='',
'Double Quote'='"',
'Single Quote'="'"),
'"')
),
mainPanel(
tableOutput('contents')
)
)
),
tabPanel("First Type",
pageWithSidebar(
headerPanel('My First Plot'),
sidebarPanel(
# "Empty inputs" - they will be updated after the data is uploaded
selectInput('xcol', 'X Variable', ""),
selectInput('ycol', 'Y Variable', "", selected = "")
),
mainPanel(
plotOutput('MyPlot')
)
)
)
)
)
)
server <- function(input, output, session) {
data <- reactive({
req(input$file1)
inFile <- input$file1
df <- read.csv(inFile$datapath, header = input$header, sep = input$sep,
quote = input$quote)
updateSelectInput(session, inputId = 'xcol', label = 'X Variable',
choices = names(df), selected = names(df))
updateSelectInput(session, inputId = 'ycol', label = 'Y Variable',
choices = names(df), selected = names(df)[2])
return(df)
})
output$contents <- renderTable({
data()
})
output$trendPlot <- renderPlotly({
# build graph with ggplot syntax
p <- ggplot(data(), aes_string(x = input$xcol, y = input$ycol)) + geom_point()
ggplotly(p)
})
}
shinyApp(ui, server)
In the above code, the following section doesn't seem to work.
output$trendPlot <- renderPlotly({
# build graph with ggplot syntax
p <- ggplot(data(), aes_string(x = input$xcol, y = input$ycol)) + geom_point()
ggplotly(p)
})

Answer 1

Actually the problem is not in output$trendPlot but in mainPanel(...)
1 : Look closely, in mainPanel, you're calling plotOutput('MyPlot') but output$MyPlot doesn't exist, only plot that exists is output$trendPlot.
2 : Note output$trendPlot <- renderPlotly({...}), return type of trendPlot is renderPlotly but plotOutput is being called at main.
So, fix is
mainPanel(
plotlyOutput('trendPlot')
)
After fixing this, output is as follows :