initial commit

bash/rna-transcription/rna_transcription.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+#
+# External tools: none.
+#
+# V1: initial version
+
+shopt -s extglob
+
+# set to mask to enable logs. 0: none, 255: all
+(( debug=2#00000000 ))
+#(( debug=2#00001111 ))
+# $1: log level (mask), then strings to display.
+debug () {
+    (( debug & $1 )) && shift && echo Line ${BASH_LINENO[0]}: "${@}" >&2
+}
+
+die () {
+    echo "${@}" >&2
+    exit 1
+}
+usage() {
+    die "usage: rna_transcription.sh [seq1] [...]"
+}
+
+declare -A complement=([G]='C'
+                       [C]='G'
+                       [T]='A'
+                       [A]='U')
+debug 1 keys/vals=${!complement[@]}/${complement[@]}
+# we will accept multiple args (out of topic for exercise), meaning that:
+#  rna_transcription.sh GCTA
+# is equivalent to
+#  rna_transcription.sh G C T A
+# or
+#  rna_transcription.sh G CTA
+dna="${@}"
+dna="${dna// /}"                        # remove spaces
+(($# > 0 )) && [[ "$dna" != +([GCTA]) ]] && die "Invalid nucleotide detected."
+
+((ldna=${#dna}))
+debug 1 "dna=$dna, length=$ldna"
+rna=""                                  # rna sequence
+
+for ((i=0; i<ldna; ++i)); do
+    seq=${dna:$i:1}
+    rna+="${complement[$seq]}"
+    debug 2 "rna=$rna"
+done
+
+echo "$rna"                             # not perfect, empty line if no args.
+exit 0
+
+# emacs/vim settings.
+# Local Variables:
+# sh-basic-offset: 4
+# indent-tabs-mode: nil
+# comment-column: 40
+# fill-column: 80
+# End:
+# vim: set tabstop=4 expandtab: