Add cartesian_product to ParallelIterator #1182
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src/iter/cartesian_product.rs
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| .into_par_iter() | ||
| .map(|i_item| repeat(i_item.clone()).zip(self.j.clone())) |
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Are the calls to into_par_iter (I already is a ParallelIterator here) and i_item.clone() (repeat will clone it repeatedly, but the first clone seems unnecessary) really required here?
I also think we can use flat_map here instead of map and flatten to possibly benefit from additional optimizations in its implementation.
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hi, you have to be careful because flat_map can end up being quite expensive compared to flat_map_iter. |
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I was trying to use cartesian products from itertools and noticed it's not implemented for rayon and has an open issue: #754
I wasn't trying to preallocate, just run a computation in the parallel iterator using a cartesian product generated by ranges. I ended up with this solution that worked for me. It's not implemented for
IndexedParallelIteratorlike suggested in the issue, only forParallelIterator. I don't know enough to know how this would impact performance.Feel free to close this if it's not done properly or out of scope. I'm also open to suggestions if there's a better way to do this.