Isolate HVR sequence and save it to a file

shell.nix

@@ -7,6 +7,7 @@ mkShell {
     R
     rPackages.immuneSIM
     rPackages.Biostrings
+    rPackages.stringr
     jdk
     # Development tools
     rPackages.languageserver

src/alignment.r

@@ -50,26 +50,51 @@ align_sequence <- function(sequence, vdj_segment) {
   ))
 }
 
-locate_cysteine <- function(sequence, v_segment) {
-  codons <- Biostrings::DNAStringSet(c("TGT", "TGC"))
-  matches <- Biostrings::matchPDict(
-    pdict = codons,
-    subject = DNAString(toString(v_segment))
-  )
-  position <- as.data.frame(intersect(matches[[1]], matches[[2]]))
-  return(position)
+handle_indels <- function(insertion, deletion, cys, alignment) {
+  ins_start <- sum(Biostrings::width(deletion[start(deletion) <= cys$start]))
+  ins_end <- sum(Biostrings::width(deletion[end(deletion) <= cys$end]))
+  shift_num <- c(0, cumsum(Biostrings::width(insertion))[-length(ins_start)])
+  shifted_ins <- IRanges::shift(insertion, shift_num)
+  gaps <- sum(width(shifted_ins[end(shifted_ins) < cys$start + ins_start])) +
+    nchar(stringr::str_extract(alignedSubject(alignment), "^-*"))
+  return(list("start" = ins_start - gaps, "end" = ins_end - gaps))
 }
 
-# TODO Extract CDR3
+get_cys_coordinates <- function(alignment) {
+  cys <- list("start" = 310, "end" = 312)
+  insertion <- unlist(Biostrings::insertion(alignment))
+  deletion <- unlist(Biostrings::deletion(alignment))
+  delta_coordinates <- handle_indels(insertion, deletion, cys, alignment)
+  cys_start <- cys$start + delta_coordinates$start
+  cys_end <- cys$end + delta_coordinates$end
+  return(list("start" = cys_start, "end" = cys_end))
+}
+
+# TODO Refactor this mess
 get_hvr_sequences <- function(sequences, vdj_segments) {
   df <- fetch_vj_sequences(sequences, vdj_segments)
   v_alignment <- parallel::mcmapply(sequences, df$v_seq, FUN = align_sequence)
-  hvr_start <- parallel::mcmapply(sequences, v_alignment, FUN = locate_cysteine)
-  hvr_start_df <- as.data.frame(t(hvr_start))
+  j_alignment <- parallel::mcmapply(sequences, df$j_seq, FUN = align_sequence)
+  cys_coordinates <- parallel::mclapply(v_alignment, FUN = get_cys_coordinates)
+  cys_df <- as.data.frame(do.call(rbind, cys_coordinates))
+  j_start <- parallel::mclapply(
+    j_alignment,
+    function(x) start(Biostrings::Views(x))
+  )
+  hvr <- Biostrings::subseq(sequences,
+    start = unlist(cys_df$start),
+    end = unlist(j_start) + 2
+  )
+  return(hvr)
+}
+
+save_data <- function(data) {
+  Biostrings::writeXStringSet(data, "data/CuReSim-HVR.fastq", format = "fastq")
 }
 
 data <- parse_data(file = "data/curesim_sequence.fastq")
-hvr_sequences <- get_hvr_sequences(
+hvr <- get_hvr_sequences(
   sequences = data[[1]],
   vdj_segments = data[[2]]
 )
+Biostrings::writeXStringSet(hvr, "data/CuReSim-HVR.fastq", format = "fastq")