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make unzip faster: seq[i]=val can be 7X faster than seq.add(val) #13448

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Merged
merged 2 commits into from
Feb 21, 2020
Merged

make unzip faster: seq[i]=val can be 7X faster than seq.add(val) #13448

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ef460da
make unzip 7X faster: seq[i] faster than seq.add
timotheecour Feb 20, 2020
107fa2b
fixup
timotheecour Feb 21, 2020
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10 changes: 5 additions & 5 deletions lib/pure/collections/sequtils.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -290,11 +290,11 @@ proc unzip*[S, T](s: openArray[(S, T)]): (seq[S], seq[T]) {.since: (1, 1).} =
unzipped2 = @['a', 'b', 'c']
assert zipped.unzip() == (unzipped1, unzipped2)
assert zip(unzipped1, unzipped2).unzip() == (unzipped1, unzipped2)
result[0] = newSeqOfCap[S](s.len)
result[1] = newSeqOfCap[T](s.len)
for elem in s:
result[0].add(elem[0])
result[1].add(elem[1])
result[0] = newSeq[S](s.len)
result[1] = newSeq[T](s.len)
for i in 0..<s.len:
result[0][i] = s[i][0]
result[1][i] = s[i][1]

proc distribute*[T](s: seq[T], num: Positive, spread = true): seq[seq[T]] =
## Splits and distributes a sequence `s` into `num` sub-sequences.
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