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Burrows–Wheeler transform: Difference between revisions
Add Swift
(Add Swift) |
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Line 1,353:
BWT("SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES") = "STEXYDST.E.IXXIIXXSSMPPS.B..EE.$.USFXDIIOIIIT"
</pre>
=={{header|Swift}}==
{{trans|Kotlin}}
<lang swift>import Foundation
private let stx = "\u{2}"
private let etx = "\u{3}"
func bwt(_ str: String) -> String? {
guard !str.contains(stx), !str.contains(etx) else {
return nil
}
let ss = stx + str + etx
let table = ss.indices.map({i in ss[i...] + ss[ss.startIndex..<i] }).sorted()
return String(table.map({str in str.last!}))
}
func ibwt(_ str: String) -> String? {
let len = str.count
var table = Array(repeating: "", count: len)
for _ in 0..<len {
for i in 0..<len {
table[i] = String(str[str.index(str.startIndex, offsetBy: i)]) + table[i]
}
table.sort()
}
for row in table where row.hasSuffix(etx) {
return String(row.dropFirst().dropLast())
}
return nil
}
func readableBwt(_ str: String) -> String {
return str.replacingOccurrences(of: "\u{2}", with: "^").replacingOccurrences(of: "\u{3}", with: "|")
}
let testCases = [
"banana",
"appellee",
"dogwood",
"TO BE OR NOT TO BE OR WANT TO BE OR NOT?",
"SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES",
"\u{2}ABC\u{3}"
]
for test in testCases {
let b = bwt(test) ?? "error"
let c = ibwt(b) ?? "error"
print("\(readableBwt(test)) -> \(readableBwt(b)) -> \(readableBwt(c))")
}</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 -> error</pre>
=={{header|Visual Basic .NET}}==
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