viewr: Better R object inspection using the FireFox JSON viewer.

viewr.R

# ================================================================================= #
#         viewr: Better R object inspection using the FireFox JSON viewer.          #
# --------------------------------------------------------------------------------- #
# Usage:                                                                            #
#   Rscript viewr.R [FILE]       # Where [FILE] has extension .Rdata or .rds        #
#                                                                                   #
# This script will only work on macOS, and assumes that you have FireFox installed! #
# --------------------------------------------------------------------------------- #
#                            Edwin Onuonga (eonu) 2020                              #   
# ================================================================================= #

if (!('jsonlite' %in% rownames(installed.packages()))) {
  install.packages('jsonlite', dependencies=TRUE, repos='http://cran.rstudio.com/')
}
suppressWarnings(suppressMessages(library(jsonlite)))
library(tools)

main <- function() {
  args <- commandArgs(trailingOnly=TRUE)
  if (length(args) == 1) {
    ext <- tolower(file_ext(args[1]))
    if (ext == 'rds') {
      objects <- 'object'
      object <- readRDS(args[1])
    } else if (ext == 'rdata') {
      load(args[1]) 
      objects <- ls()[!(ls() %in% c('ext', 'args'))]
    } else {
      message('Invalid extension - expected .Rdata or .rds.')
      quit(status=0)
    }
    
    if (length(objects) == 0) {
      message('Unable to find any objects in the namespace.')
      quit(status=0)
    } else if (length(objects) == 1) {
      if (ext == 'rds') {
        name <- objects[1]
      } else if (ext == 'rdata') {
        name <- objects[1]
        object <- get(name) 
      }
    } else {
      valid = FALSE
      while (!valid) {
        cat(sprintf("\033[1mFound %s objects. Which one to load?\033[0m\n", length(objects)))
        for (i in 1:length(objects)) {
          cat(sprintf("  %s: %s\n", i, objects[i]))
        }
        cat('Enter number or name: ')
        input <- readLines('stdin', n=1)
        cat('\n')
        if (input %in% objects) {
          name <- input
          object <- get(name)
          valid = TRUE
        } else if (!grepl('\\D', input)) {
          idx <- as.integer(input)
          if (idx <= length(objects)) {
            name <- objects[idx]
            object <- get(name)
            valid = TRUE
          } else {
            message(sprintf('Invalid input - expected a number from 1 to %s.', length(objects)))
          }
        } else {
          message('Invalid input.')
        }
      }
    }
    
    json <- toJSON(object, pretty=TRUE)
    filename <- sprintf('.%s.json', name)
    conn <- file(filename)
    writeLines(json, conn)
    close(conn)
    
    tryCatch({
      system(sprintf('open -a Firefox %s', filename))
      cat('Press enter to end: ')
      invisible(readLines('stdin', n=1))
    }, error = function(e) {
      # TODO
    }, finally = {
      if (file.exists(filename)) file.remove(filename)
    })
  } else {
    cat('\033[4mviewr\033[0m: Better R object inspection using the FireFox JSON viewer.\n\n')
    cat('\033[1mUsage\033[0m:\n')
    cat('  Rscript viewr.R [FILE]    \033[37m#\033[0m \033[90mWhere [FILE] has extension .Rdata or .rds\033[0m\n')
  }
}

main()