Specific scenario consultation

[Matan Tennenhaus]

Hi,

I am trying to find an optimized algorithm using roaring API for my problem.

I have 3 existing bitmaps: a, b, c.

The algorithm:

temp = a & b;

c += temp;

a -= temp;

b -= temp;

(remove from a and b the intersection, and add it to c).

I cannot find API's which let me cache somehow the results and used it, and i feel i need to do some calculations multiple times..

I would be glad to get recommendations on how to use roaring API the most efficiently in this scenario.

Many thanks in advance,

Matan.

[Daniel Lemire]

Can you illustrate your issue using software code? Please elaborate on the issue.

[Matan Tennenhaus]

    /* intersect */
    tmp = roaring64_bitmap_and(al, bl);
    /* al = al - tmp*/
    roaring64_bitmap_andnot_inplace(al, tmp);
    /* bl = bl - intr */
    roaring64_bitmap_andnot_inplace(bl, tmp);
    /* cl = cl + tmp*/
    roaring64_bitmap_or_inpalce(cl, tmp);

ב-יום רביעי, 25 בספטמבר 2024 בשעה 00:55:01 UTC+3, Daniel Lemire כתב/ה:

[Daniel Lemire]

Your code looks fine to me. Of course, we have that...

a -= (a&b)

is equal to

a -= b

But that's just basic set theory... I don't see anything specific to Roaring bitmaps in the computation you are doing. 

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