Burrows–Wheeler transform: Difference between revisions

=={{header|Groovy}}==

{{trans|Java}}

<lang groovy>class BWT {

private static final String STX = "\u0002"

private static final String ETX = "\u0003"

private static String bwt(String s) {

if (s.contains(STX) || s.contains(ETX)) {

throw new IllegalArgumentException("String cannot contain STX or ETX")

}

String ss = STX + s + ETX

List<String> table = new ArrayList<>()

for (int i = 0; i < ss.length(); i++) {

String before = ss.substring(i)

String after = ss.substring(0, i)

table.add(before + after)

}

Collections.sort(table)

StringBuilder sb = new StringBuilder()

for (String str : table) {

sb.append(str[str.length() - 1])

}

return sb.toString()

}

private static String ibwt(String r) {

int len = r.length()

List<String> table = new ArrayList<>()

for (int i = 0; i < len; ++i) {

table.add("")

}

for (int j = 0; j < len; ++j) {

for (int i = 0; i < len; ++i) {

table[i] = r[i] + table[i]

}

Collections.sort(table)

}

for (String row : table) {

if (row.endsWith(ETX)) {

return row.substring(1, len - 1)

}

}

return ""

}

private static String makePrintable(String s) {

// substitute ^ for STX and | for ETX to print results

return s.replace(STX, "^").replace(ETX, "|")

}

static void main(String[] args) {

List<String> tests = new ArrayList<>()

tests.add("banana")

tests.add("appellee")

tests.add("dogwood")

tests.add("TO BE OR NOT TO BE OR WANT TO BE OR NOT?")

tests.add("SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES")

tests.add("\u0002ABC\u0003")

for (String test : tests) {

println(makePrintable(test))

print(" --> ")

String t = ""

try {

t = bwt(test)

println(makePrintable(t))

} catch (IllegalArgumentException e) {

println("ERROR: " + e.getMessage())

}

String r = ibwt(t)

printf(" --> %s\n\n", r)

}

}

}</lang>

{{out}}

<pre>banana

--> |annb^aa

--> banana

appellee

--> |e^elplepa

--> appellee

dogwood

--> |do^oodwg

--> dogwood

TO BE OR NOT TO BE OR WANT TO BE OR NOT?

--> |?OOORREEETTRTW BBB ATTT NNOOONOO^

--> TO BE OR NOT TO BE OR WANT TO BE OR NOT?

SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES

--> |STEXYDST.E.IXXIIXXSSMPPS.B..EE.^.USFXDIIOIIIT

--> SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES

^ABC|

--> ERROR: String cannot contain STX or ETX

--> </pre>