R shiny app | 网页应用 空格分隔的文本文件在线转csv

shiny 能快速把R程序以web app的形式提供出来，方便使用，降低技术使用门槛。

本文提供的示例：把空格分隔的txt文件转为逗号分隔的csv文件。

前置依赖：需要有R环境(v4.2.0)，安装shiny包(v1.9.1)。括号内是我使用的版本。

install.packages(“shiny”)

1.运行与效果

• 文件名：script/app3/app.R
• 运行: > shiny::runApp(“script/app3/”)
• 关闭：关闭浏览器。

1. 左上角：上传文件，
2. 右侧：预览效果
3. 右下角：下载csv文件
   

2.文件内容

script/app3/app.R 如下:

library(shiny)
library(bslib)# Define UI for slider demo app ----
ui <- page_sidebar(# App title ----title = "Blank space txt to csv | v0.0.1",# Sidebar panel for inputs ----sidebar = sidebar(# Input: Select a file ----fileInput("file1","Choose TXT File",multiple = TRUE,accept = c("text/csv","text/comma-separated-values,text/plain","text/blank-separated-values,text/plain",".csv")),tags$hr(),sliderInput("num","show number:",min = 2,max = 1000,value = 10),# Horizontal line ----tags$hr(),# Input: Checkbox if file has header ----checkboxInput("header", "Header", TRUE),# Input: Select separator ----radioButtons("sep","Separator",choices = c(Comma = ",",Semicolon = ";",Blank = " ",Tab = "\t"),selected = " "),# Input: Select quotes ----radioButtons("quote","Quote",choices = c(None = "","Double Quote" = '"',"Single Quote" = "'"),selected = ''),# Horizontal line ----tags$hr(),# Input: Select number of rows to display ----radioButtons("disp","Display",choices = c(Head = "head",All = "all"),selected = "head"),# ButtondownloadButton("downloadData", "Download csv")),# Output: Data file ----tableOutput("contents")
)# Define server logic to read selected file ----
server <- function(input, output) {output$contents <- renderTable({# input$file1 will be NULL initially. After the user selects# and uploads a file, head of that data file by default,# or all rows if selected, will be shown.req(input$file1)df <- read.csv(input$file1$datapath,header = input$header,sep = input$sep,quote = input$quote)if (input$disp == "head") {return(head(df, n=input$num))} else {return(df, n=input$num)}})# Downloadable csv of selected dataset ----output$downloadData <- downloadHandler(filename = function() {req(input$file1)paste(input$file1$datapath, ".csv", sep = "")},content = function(file) {req(input$file1)df <- read.csv(input$file1$datapath,header = input$header,sep = input$sep,quote = input$quote)write.csv(df, file, row.names = FALSE, quote=F)})
}if(0){# show blank separated txt file with headerrunApp("script/app3/")
}# Create Shiny app ----
shinyApp(ui, server)

Ref

• https://shiny.posit.co/r/getstarted/shiny-basics/lesson1/

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