fix: allow empty input tables

scripts/merge_tables.R

@@ -7,8 +7,12 @@
 #################
 
 # Import required packages
-if ( suppressWarnings(suppressPackageStartupMessages(require("optparse"))) == FALSE ) { stop("[ERROR] Package 'optparse' required! Aborted.") }
-if ( suppressWarnings(suppressPackageStartupMessages(require("dplyr"))) == FALSE ) { stop("[ERROR] Package 'dplyr' required! Aborted.") }
+if (suppressWarnings(suppressPackageStartupMessages(require("optparse"))) == FALSE) {
+  stop("[ERROR] Package 'optparse' required! Aborted.")
+}
+if (suppressWarnings(suppressPackageStartupMessages(require("dplyr"))) == FALSE) {
+  stop("[ERROR] Package 'dplyr' required! Aborted.")
+}
 
 
 #######################
@@ -21,9 +25,10 @@ script <- sub("--file=", "", basename(commandArgs(trailingOnly=FALSE)[4]))
 # Build description message
 description <- "Merge miRNAs quantification tables.\n"
 author <- "Author: Paula Iborra, Biozentrum, University of Basel"
-version <- "Version: 1.0.0 (JUN-2019)"
-requirements <- "Requires: optparse"
-msg <- paste(description, author, version, requirements, sep="\n")
+mantainer <- "Refactor and documentation: Iris Mestres"
+version <- "Version: 1.1.0 (FEB-2024)"
+requirements <- "Requires: optparse, dplyr"
+msg <- paste(description, author, mantainer, version, requirements, sep="\n")
 
 # Define list of arguments
 option_list <- list(
@@ -73,7 +78,18 @@ option_list <- list(
 )
 
 # Parse command-line arguments
-opt_parser <- OptionParser(usage=paste("Usage:", script, "[OPTIONS] --input_dir <path/to/input/files>\n", sep=" "), option_list = option_list, add_help_option=FALSE, description=msg)
+opt_parser <-
+  OptionParser(
+    usage = paste(
+      "Usage:",
+      script,
+      "[OPTIONS] --input_dir <path/to/input/files>\n",
+      sep = " "
+    ),
+    option_list = option_list,
+    add_help_option = FALSE,
+    description = msg
+  )
 opt <- parse_args(opt_parser)
 
 # Re-assign variables
@@ -92,19 +108,80 @@ if ( is.null(in.dir) ) {
 ###    FUNCTIONS   ###
 ######################
 
-merge_tables <- function(cwd, prefix){
-  dataFiles <- dir(cwd, prefix, full.names=TRUE)
+#' Read and process input table
+#'
+#' `get_table()` uses `tryCatch()` to read the file in `tbl_pth`. If the table
+#' is empty and an error is raised, a data frame is created.
+#'
+#' @param tbl_pth Path to the input table.
+#' @param prefix String to be removed from the input file name. It must be
+#'   present in all the tables to be merged.
+#'
+#' @returns `get_table()` returns a data frame containing the miRNA species to
+#'   be counted in first column, named `ID`, and their counts in that file in
+#'   the second one. The name of the second column in the data frame is obtained
+#'   by removing the `prefix` from the input file name. If no `prefix` is given,
+#'   the whole file name is used.
+#'
+#'   If the input file is empty, the returned data frame will consist on one row
+#'   with a `NA` in both fields.
+#'
+#' @seealso [tryCatch()] which this function uses.
+get_table <- function(tbl_pth, prefix) {
+  sample <- gsub(prefix, "", tbl_pth)
+  fields <- c("ID", basename(sample))
+
+  tryCatch(
+    expr = {
+      table <- read.table(tbl_pth, sep = '\t', col.names = fields)
+      return(table)
+    },
+    error = function(e) {
+      table <- data.frame(matrix(NA, ncol = 2, nrow = 1))
+      colnames(table) <- fields
+      return(table)
+    }
+  )
+}
+
+#' Merge tables with the same prefix
+#'
+#' `merge_tables()` takes all the files in `cwd` that start with `prefix` and
+#' merge them keeping all the miRNA species present in each of the tables.
+#'
+#' @details The function `get_table()` is used to make sure that even if an
+#'   empty input file is given, the merge can still be done. Thus, before
+#'   returning the merged table, the row with a `NA` in the `ID` field, if any,
+#'   is removed.
+#'
+#'   The function `dplyr::full_join()` method is used for the merge, therefore,
+#'   if a miRNA species in `ID` is missing in any of the tables being joined,
+#'   its value is set to `NA` in that column.
+#'
+#' @param cwd Path to the input tables directory.
+#' @param prefix String used in all the tables to be selected for the merge. If
+#'    not provided, all the files in `cwd` are used.
+#'
+#' @returns `merge_tables()` returns a single data frame, `mat`, with all the
+#'   miRNA species present in the input tables in the first column, `ID`, and
+#'   their counts. Each input file has it own column.
+#'
+#'   If all the input tables are empty, the output consists only on the table's
+#'   header, and if no files starting with `prefix` are found, nothing is
+#'   returned.
+#'
+#' @seealso [get_table()], [dplyr::full_join()] which this function uses.
+merge_tables <- function(cwd, prefix) {
+  dataFiles <- dir(cwd, prefix, full.names = TRUE)
   mat <- NULL
+
   if (length(dataFiles)) {
-    mat <- read.table(dataFiles[1], sep='\t')
-    sample <- gsub(prefix, "", dataFiles[1])
-    colnames(mat)[2] <- basename(sample)
-    for (i in seq_len(length(dataFiles)-1)) {
-       mat <- full_join(mat, read.table(dataFiles[i+1], sep = "\t"), by='V1')
-       sample <- gsub(prefix, "", dataFiles[i+1])
-       colnames(mat)[i + 2] <- basename(sample)
+    mat <- get_table(dataFiles[1], prefix)
+
+    for (i in seq_len(length(dataFiles) - 1)) {
+      mat <- full_join(mat, get_table(dataFiles[i + 1], prefix), by = "ID")
     }
-    colnames(mat)[1] <- "ID"
+    mat <- filter(mat, !is.na(ID))
   }
   return(mat)
 }
@@ -113,22 +190,35 @@ merge_tables <- function(cwd, prefix){
 ###      MAIN      ###
 ######################
 # Write log
-if ( verb ) cat("Creating output directory...\n", sep="")
+if (verb)
+  cat("Creating output directory...\n", sep = "")
 
 # Create output directories
-dir.create(dirname(out.file), recursive=TRUE, showWarnings=FALSE)
+dir.create(dirname(out.file),
+           recursive = TRUE,
+           showWarnings = FALSE)
 
 # Write log
-if ( verb ) cat("Creating table...\n", sep="")
+if (verb)
+  cat("Creating table...\n", sep = "")
 
 # Create table from input directory files
-myTable <- merge_tables(cwd=in.dir, prefix=prefix)
+myTable <- merge_tables(cwd = in.dir, prefix = prefix)
 
 # Write log
-if ( verb ) cat(paste("Writing table: ", out.file, "\n", sep=""), sep="")
+if (verb)
+  cat(paste("Writing table: ", out.file, "\n", sep = ""), sep = "")
 
 # Writing table
-write.table(myTable, out.file, row.names=FALSE, col.names=TRUE, quote=FALSE, sep="\t")
+write.table(
+  myTable,
+  out.file,
+  row.names = FALSE,
+  col.names = TRUE,
+  quote = FALSE,
+  sep = "\t"
+)
 
 # Write log
-if ( verb ) cat("Done.\n", sep="")
+if (verb)
+  cat("Done.\n", sep = "")