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Improve count performance #40564

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Nov 18, 2021
Merged

Improve count performance #40564

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Improve count performance
bkamins Apr 22, 2021
72651df
Update base/reduce.jl
bkamins Apr 22, 2021
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6 changes: 4 additions & 2 deletions base/reduce.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -1200,10 +1200,12 @@ count(itr; init=0) = count(identity, itr; init)

count(f, itr; init=0) = _simple_count(f, itr, init)

function _simple_count(pred, itr, init::T) where {T}
_simple_count(pred, itr, init) = _simple_count_helper(Generator(pred, itr), init)

function _simple_count_helper(g, init::T) where {T}
n::T = init
for x in itr
n += pred(x)::Bool
n += x::Bool
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Is this just n += true now?

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no pred can return true or false, e.g.:

julia> collect(Base.Generator(ismissing, [1,missing,2]))
3-element Vector{Bool}:
 0
 1
 0

and we still need ::Bool assertion

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Oh yeah, somehow I thought the first argument was a filter with this syntax.

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That is why I was surprised that the compiler does not vectorize it (the only thing I do is introduce Generator wrapper and add a function barrier - but both are needed to force vectorization)

end
return n
end
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