stack_05302022

TITLE: Shiny: Compare two dfs, highlight differences, edit + download new df

My goal is to build a Shiny app where I can upload two dataframes and the app will:

* Automatically highlight discrepancies between the two dataframes
* Allow direct editing to the dataframe
* Allow me to download the newly-edited dataframe


I have created a working reprex using gt, but so far I am unable to add editing/downloading capability, as I couldn't translate gt's highlighting into something compatible with DT or rhandsomtable. Not included here, but I also was able to replicate [this tutorial][1] on rhandsomtable to allow upload of two dataframes, but I couldn't add the feature to highlight discrepant cells. I would appreciate any recommendations or directions on packages, thank you!

## uses gt table, not editable

```
library(shiny)
library(gt)
library(rhandsontable)
library(tidyverse)
library(shinythemes)
library(rsconnect)
library(DT)

dat1 <- data.frame(
  emp_id = c(1:5),
  emp_name = c("Rick","Dan","Michelle","Ryan","Gary"),
  salary = c(623.3,515.2,611.0,735.0,844.25))

dat2 <- data.frame(
  emp_id = c(1:5),
  emp_name = c("Rick","Dan","Michelle","Ryan","Gary"),
  salary = c(623.3,515.2,611.0,729.0,843.25))

ui <-  navbarPage("This is my Shiny app.",
                  theme = shinytheme("flatly"),
                  tabPanel("Upload",
                           titlePanel("Upload your datafiles"),
                           sidebarLayout(
                             sidebarPanel(

                               ## File 1
                               fileInput('file1', 'Data Entry #1',
                                         accept=c('text/csv',
                                                  'text/comma-separated-values,text/plain',
                                                  '.csv')),
                               tags$hr(),

                               ## File 2
                               fileInput('file2', 'Data Entry #2',
                                         accept=c('text/csv',
                                                  'text/comma-separated-values,text/plain',
                                                  '.csv')),
                               tags$hr(),

                             ),

                             mainPanel(gt_output("contents"))
                           )
                  ),
)

server <- function(input, output, session) {

  df1 <- reactive({ dat1
    #inFile <- input$file1
    #if (is.null(input$file1))
    #  return(NULL)
    #read.csv(inFile$datapath)
  })

  df2 <- reactive({ dat2
    #inFile <- input$file2
    #if (is.null(input$file2))
    #  return(NULL)
    #read.csv(inFile$datapath)
  })

  compared <- reactive({

    req(df1())
    req(df2())

    tbl_diffs <- which(df1() != df2(), arr.ind = TRUE)
    tbl_compare <- df2() %>%
      gt()
    for (i in seq_len(nrow(tbl_diffs))) {
      tbl_compare <- tbl_compare %>%
        tab_style(
          style = list(
            cell_fill(color = "#FFFF00")
          ),
          locations = cells_body(
            columns = tbl_diffs[[i, "col"]],
            rows = tbl_diffs[[i, "row"]]
          )
        )
    }
    tbl_compare
  })

  output$contents <- render_gt(
    compared()
  )
}

shinyApp(ui = ui, server = server)
```

## failed attempt at dt

```
library(shiny)
library(gt)
library(rhandsontable)
library(tidyverse)
library(shinythemes)
library(rsconnect)
library(DT)

dat1 <- data.frame(
  emp_id = c(1:5),
  emp_name = c("Rick","Dan","Michelle","Ryan","Gary"),
  salary = c(623.3,515.2,611.0,735.0,844.25))

dat2 <- data.frame(
  emp_id = c(1:5),
  emp_name = c("Rick","Dan","Michelle","Ryan","Gary"),
  salary = c(623.3,515.2,611.0,729.0,843.25))

ui <-  navbarPage("This is my Shiny app.",
                  theme = shinytheme("flatly"),
                  tabPanel("Upload",
                           titlePanel("Upload your datafiles"),
                           sidebarLayout(
                             sidebarPanel(

                               ## File 1
                               fileInput('file1', 'Data Entry #1',
                                         accept=c('text/csv',
                                                  'text/comma-separated-values,text/plain',
                                                  '.csv')),
                               tags$hr(),

                               ## File 2
                               fileInput('file2', 'Data Entry #2',
                                         accept=c('text/csv',
                                                  'text/comma-separated-values,text/plain',
                                                  '.csv')),
                               tags$hr(),

                             ),

                             mainPanel(dataTableOutput("contents"))
                           )
                  ),
)

server <- function(input, output, session) {

  df1 <- reactive({ dat1
    #inFile <- input$file1
    #if (is.null(input$file1))
    #  return(NULL)
    #read.csv(inFile$datapath)
  })

  df2 <- reactive({ dat2
    #inFile <- input$file2
    #if (is.null(input$file2))
    #  return(NULL)
    #read.csv(inFile$datapath)
  })

  compared <- reactive({

    req(df1())
    req(df2())

    tbl_diffs <- which(df1() != df2(), arr.ind = TRUE) %>% as.data.frame()
    tbl_compare <- df2() %>% as.data.frame()

    tbl_gt_B <- df2() %>% as.data.frame()

    for (i in seq_len(nrow(tbl_diffs))) {
      tbl_gt_B <-
        formatStyle(tbl_gt_B,
                    color = "yellow",
                    columns = tbl_diffs[[i, "col"]],
                    rows = tbl_diffs[[i, "row"]]) }
    tbl_compare
  })

  output$contents <- renderDataTable(
    compared()
  )
}

shinyApp(ui = ui, server = server)
```


  [1]: http://stla.github.io/stlapblog/posts/shiny_editTable.html