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FIXUP: More comments about shuffle

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This commit is contained in:
Joanna Hulboj 2023-01-27 18:03:13 +00:00
parent 8791a44e01
commit 9a559b5475
2 changed files with 10 additions and 2 deletions
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8
src/Common/shuffle.h
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@ -6,6 +6,10 @@
/* Reorders the elements in the given range [first, last) such that each
* possible permutation of those elements has equal probability of appearance.
*
* for i ∈ [0, n-2):
* j ← random from ∈ [i, n)
* swap arr[i] ↔ arr[j]
*/
template <typename Iter, typename Rng>
void shuffle(Iter first, Iter last, Rng && rng)
@ -28,6 +32,10 @@ void shuffle(Iter first, Iter last, Rng && rng)
* [first, first + limit) is a random subset of the original range.
* [first + limit, last) shall contain the elements not in [first, first + limit)
* in undefined order.
*
* for i ∈ [0, limit):
* j ← random from ∈ [i, n)
* swap arr[i] ↔ arr[j]
*/
template <typename Iter, typename Rng>
void partial_shuffle(Iter first, Iter last, size_t limit, Rng && rng)

4
src/Functions/array/arrayShuffle.cpp
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@ -36,7 +36,7 @@ struct FunctionArrayShuffleTraits
static constexpr auto has_limit = false; // Permute the whole array
static ColumnNumbers getArgumentsThatAreAlwaysConstant() { return {1}; }
static constexpr auto max_num_params = 2; // array[, seed]
static constexpr auto seed_param_idx = 1;
static constexpr auto seed_param_idx = 1; // --------^^^^
};
/** Partial shuffle array elements
@ -50,7 +50,7 @@ struct FunctionArrayPartialShuffleTraits
static constexpr auto has_limit = true;
static ColumnNumbers getArgumentsThatAreAlwaysConstant() { return {1, 2}; }
static constexpr auto max_num_params = 3; // array[, limit[, seed]]
static constexpr auto seed_param_idx = 2;
static constexpr auto seed_param_idx = 2; // ----------------^^^^
};
template <typename Traits>