回答編集履歴

3

2024/09/21 07:05

投稿

melian
melian

スコア20592

test CHANGED
@@ -11,3 +11,35 @@
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  # [0, 0, 0, 0, 1, 2, 3, 0, 0, 1, 2, 0, 0]
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  ```
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+
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+ ### 追記
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+
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+ ```julia
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+ $ julia
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+ help?> zip
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+ search: zip
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+
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+ zip(iters...)
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+
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+ Run multiple iterators at the same time, until any of them is exhausted.
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+ The value type of the zip iterator is a tuple of values of its subiterators.
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+ ```
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+
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+ `zip()`(イテレータ)を利用する方が3倍程度速く、メモリ使用量も少ないです。
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+ ```julia
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+ using DataFrames
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+ import ShiftedArrays: lag
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+ using BenchmarkTools
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+
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+ test = DataFrame(a=[1,2,3,2,2,2,2,4,5,5,5,6,7])
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+
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+ @btime accumulate((acc, i) -> i ? acc+1 : 0,
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+ test.a .== lag(test.a, default=test.a[1]-1))
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+ @btime accumulate((acc, (i, j)) -> i==j ? acc+1 : 0,
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+ zip(test.a, lag(test.a, default=0));
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+ init=test.a[1]-1)
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+
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+ # 3.859 μs (22 allocations: 1.59 KiB)
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+ # 1.304 μs (8 allocations: 416 bytes)
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+ ```
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+

2

2024/09/21 06:30

投稿

melian
melian

スコア20592

test CHANGED
@@ -5,8 +5,8 @@
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  test = DataFrame(a=[1,2,3,2,2,2,2,4,5,5,5,6,7])
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- newList = accumulate((acc, (i, j)) -> i==j ? acc+1 : 0, zip(test.a, lag(test.a, default=0));
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+ newList = accumulate((acc, i) -> i ? acc+1 : 0,
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- init=test.a[1]-1)
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+ test.a .== lag(test.a, default=test.a[1]-1));
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  println(newList)
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  # [0, 0, 0, 0, 1, 2, 3, 0, 0, 1, 2, 0, 0]

1

2024/09/21 04:17

投稿

melian
melian

スコア20592

test CHANGED
@@ -5,7 +5,7 @@
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  test = DataFrame(a=[1,2,3,2,2,2,2,4,5,5,5,6,7])
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- newList = accumulate((acc, i) -> i[1]==i[2] ? acc+1 : 0, zip(test.a, lag(test.a, default=0));
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+ newList = accumulate((acc, (i, j)) -> i==j ? acc+1 : 0, zip(test.a, lag(test.a, default=0));
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  init=test.a[1]-1)
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  println(newList)
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