R shiny: Get table to only display the top x rows - r

Question

Context: I'm trying to make a R shiny server which takes file uploads and displays it in a table in the UI. The file can either be in csv, txt or tsv, meaning read.csv() is not appropriate. Also the table output can change at anytime depending on the user's input of the radiobuttons to determine the delimiter.
Problem: I can't seem to make the table only display the top x number of rows from the file. Does anyone know any possible solutions?
Attempted solutions:
I've tried using renderDataTable function, however it had an error saying that data() is needs to be a matrix or dataFrame. It doesn't make sense since read.table() function would return a dataframe(https://www.rdocumentation.org/packages/utils/versions/3.6.2/topics/read.table). And data <-reactive would mean data is a dataFrame.
Server
server <- function(input, output, session) {
output$distPlot <- renderPlot({
hist(rnorm(input$obs), col = 'darkgray', border = 'white')
})
observe({
# DEFile from fileInput() function
ServerDEFile <- req(input$DEFile)
# extensions tool for format validation
extDEFile <- tools::file_ext(ServerDEFile$datapath)
if(is.null(input$DEFile)){return()
}else{
if (extDEFile == "txt") {
label = paste("Delimiters for", extDEFile, "file")
choice <-c(Comma=",", Semicolon=";", Tab="\t", Space=" ")
}else if (extDEFile == "tsv") {
label = paste("Delimiter: Tab")
choice <- (Tab="\t")
}else {
label = paste("Delimiter: Comma")
choice <- (Comma=",")
}
updateRadioButtons(session, "sepButton", label = label, choices = choice)
}
})
# reactive converts the upload file into a reactive expression known as data
data <- reactive({
# DEFile from fileInput() function
ServerDEFile <- input$DEFile
# extensions tool for format validation
extDEFile <- tools::file_ext(ServerDEFile$datapath)
# file format checking
req(ServerDEFile)
# validate(need(extDEFile == c("csv", "tsv", "txt"), "Please upload a csv, tsv or txt file."))
# convert data into file format
if(is.null(extDEFile)){return()}
read.table(file=ServerDEFile$datapath, sep=input$sepButton)
})
# creates reactive table called DEFileContent
output$DEFileContent <- renderTable({
if(is.null(data())){return ()}
data()
})
# handles rendering of reactive object on tb on ui
output$UIDEContent <- renderUI({
tableOutput("DEFileContent")
})
}
UI
library(shinyWidgets)
library(DT)
library(shiny)
ui <- fluidPage(
titlePanel(title=div(img(src="ODClogo.png", height = 50), "OutDeCo")),
#navbarPage is top menu bar
navbarPage("",
#tabPanel is each tab in the navbarPage
# Assess DE tab
tabPanel(
title="Assess DE",
dropdown(
# title of sidepanel
tags$h3("Options"),
# inputs in the sidepanel
fileInput("DEFile", "Choose DE File",
accept = c(
".csv",
".tsv",
".txt"
)
),
# button for selecting delimiter, default is nothing until file is selected and handled in server side
radioButtons(inputId = 'sepButton', label = 'Delimiter Selector', choices = c(Default=''), selected = ''),
# side panel characteristics
style = "gradient", icon = icon("cog"),
status = "primary", width = "300px",
animate = animateOptions(
enter = animations$fading_entrances$fadeInLeftBig,
exit = animations$fading_exits$fadeOutLeftBig
)
),
navlistPanel(
tabPanel(
title="Cluster Genes",
"Cluster genes Page",
# Navigation Bar for types of plots inside cluster
tabsetPanel(
tabPanel(
title="View file",
mainPanel(
uiOutput("UIDEContent")
)
),
tabPanel(
title="Plot 2"
),
tabPanel(
title="Plot 3"
)
),
),
),
)
),
)