Shiny: Use filtered datatable in further functions

How do you use the filtered output from datatables in further functions? I am making a Shiny app where the data is uploaded and filtered by the user with a datatable. I then want to use the filtered data to perform some functions. I give one below (calcs()). I am getting the Error: invalid 'x' type in 'x && y'.

The .csv file is:

Day: 1,2,3
Subject: 1,2,3
Location: 1,1,2

ui.R
    shinyUI(fluidPage(theme = shinytheme("spacelab"),
                      # title and subtitles
                      titlePanel(
                        h1(HTML("</b>Test App</b>"),
                           style="text-align:center")),
                      sidebarLayout(
                        sidebarPanel(
                          fileInput("file1", "Choose Input .csv File",
                                    multiple = TRUE,
                                    accept = c("text/csv",
                                               "text/comma-separated-values,text/plain",
                                               ".csv")
                          ),
                          downloadButton("downloadData",
                                         "Download Results (.xlsx)")
                        ),
                        mainPanel(title = "Raw Data",
                                  DT::dataTableOutput("table"),
                        )
                      )
    ))

server.R
shinyServer <- function(input, output, session) {
  datasetInput <- reactive({
    if(is.null(input$file1))     return(NULL) 
    csv_data <- read.csv(input$file1$datapath)
  })
  output$table = DT::renderDataTable(datasetInput(),
                                     filter = "top",
                                     server = "FALSE")
  calcs <- reactive({
    remove_pos_baseline <- as.data.frame(input$table_rows_all) %>%
      group_by(Location) %>%
      mutate(count = first(Subject))
  })
  data_list <- reactive({
    list(
      table = calcs(),
      patient_results = datasetInput()
    )
  })
  output$downloadData <- downloadHandler(
    filename = function() {
      paste("Output", datasetInput()$Location[1], "-", Sys.Date(), ".xlsx", sep="")
    },
    content = function(file) {
      write_xlsx(data_list(), path = file)
    }
  )
}