Added load_fasta from rhierbaps

R/load_fasta.R

@@ -0,0 +1,56 @@
+#' load_fasta
+#'
+#' Loads a fasta file into matrix format ready for
+#' running the hierBAPS algorithm.
+#'
+#' @param msa Either the location of a fasta file or ape DNAbin object containing the multiple sequence alignment data to be clustered
+#' @param keep.singletons A logical indicating whether to consider singleton mutations in calculating the clusters
+#'
+#' @return A character matrix with filtered SNP data
+#'
+#' @examples
+#' msa <- system.file("extdata", "seqs.fa", package = "rhierbaps")
+#' snp.matrix <- load_fasta(msa)
+#' @export
+load_fasta <- function(msa, keep.singletons=FALSE) {
+
+  #Check inputs
+  if(class(msa)=="character"){
+    if (!file.exists(msa)) stop("Invalid msa or the file does not exist!")
+    seqs <- ape::read.FASTA(msa)
+  } else if(class(msa)=="matrix"){
+    seqs <- ape::as.DNAbin(msa)
+  } else if(class(msa)=="DNAbin"){
+    seqs <- msa
+  } else{
+    stop("incorrect input for msa!")
+  }
+  if (!is.logical(keep.singletons)) stop("Invalid keep.singletons! Must be on of TRUE/FALSE.")
+
+  #Load sequences using ape. This does a lot of the checking for us.
+  seq_names <- labels(seqs)
+  seqs <- as.character(as.matrix(seqs))
+  rownames(seqs) <- seq_names
+  seqs[is.na(seqs)] <- "-"
+
+  if (nrow(seqs)<3) stop("Less than 3 sequences!")
+  warning("Characters not in acgtnACGTN- will be treated as missing (-)...")
+
+  #Remove conserved columns
+  conserved <- colSums(t(t(seqs)==seqs[1,]))==nrow(seqs)
+  seqs <- seqs[, !conserved]
+
+  if(!keep.singletons){
+    #remove singletons as they are uninformative in the algorithm
+    is_singleton <- apply(seqs, 2, function(x){
+      tab <- table(x)
+      return(x %in% names(tab)[tab==1])
+    })
+    seqs[is_singleton] <- "-"
+  }
+
+  #Convert gaps and unknowns to same symbol
+  seqs[seqs=="n"] <- "-"
+
+  return(seqs)
+}