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Set intersection in C++ on the keys of a map


Set intersection in C++ on the keys of a map

By : Ram Pal
Date : October 17 2020, 06:10 AM
I wish did fix the issue. You need to modify the lambda slightly. The comparison operation is operator<, not operator==, so you need something like:
code :
std::set_intersection
    (word_count1.begin(), word_count1.end(), 
     word_count2.begin(), word_count2.end(), 
     inserter (intersection, intersection.begin()),
     [](const std::pair<std::string, int> &p1, const std::pair<std::string, int> &p2)
         {return p1.first < p2.first;});
 [](const auto &p1, const auto &p2)
     {return p1.first < p2.first;});


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Getting intersection of a keys of a map

Getting intersection of a keys of a map


By : sammuse
Date : March 29 2020, 07:55 AM
it fixes the issue EDIT : must use a copy of the first set in map (thanks to Bohemian)
In pseudo-code, you could have
code :
Init result set to null to know it is still not initialized

Loop for each key in check_set
    if result is null then result = map{key} // take first set
    else result = intersection(result, map{key}) // and keep on intersecting
Set<Integer> result = null;
for (String key: check_set) {
    if (result == null) {
        result = new HashSet<Integer>(map.get(key));
    }
    else {
        result.retainAll(map.get(key));
    }
}
How to get the intersection of two arrays by keys?

How to get the intersection of two arrays by keys?


By : deodato
Date : March 29 2020, 07:55 AM
it should still fix some issue I want to save certain values from $_POST into a file. But I only want values where the key is in the array $lang. , Try this :
code :
// Combining both arrays into one.
$combined_array = array_merge($_POST, $lang);
$fh = fopen('name.php', 'w');
foreach($combined_array as $key => $value){
    fwrite($fh , $key .'-' . $value );
    fwrite($fh ,"\n" );
}
Best way to get intersection of keys of two objects?

Best way to get intersection of keys of two objects?


By : terroblaxxx
Date : March 29 2020, 07:55 AM
hop of those help? I have two object literals like so: , A solution without indexOf.
code :
var firstObject = { x: 0, y: 1, z: 2, a: 10, b: 20, e: 30 },
    secondObject = { x: 0, y: 1, z: 2, a: 10, c: 20, d: 30 };

function intersection(o1, o2) {
    return Object.keys(o1).concat(Object.keys(o2)).sort().reduce(function (r, a, i, aa) {
        if (i && aa[i - 1] === a) {
            r.push(a);
        }
        return r;
    }, []);
}

document.write('<pre>' + JSON.stringify(intersection(firstObject, secondObject), 0, 4) + '</pre>');
var firstObject = { x: 0, y: 1, z: 2, a: 10, b: 20, e: 30 },
    secondObject = { x: 0, y: 1, z: 2, a: 10, c: 20, d: 30 };

function intersection(o1, o2) {
    return Object.keys(o1).filter({}.hasOwnProperty.bind(o2));
}

document.write('<pre>' + JSON.stringify(intersection(firstObject, secondObject), 0, 4) + '</pre>');
Ray Tracing - Geometric Sphere Intersection - Intersection function returns true for all rays despite no intersection

Ray Tracing - Geometric Sphere Intersection - Intersection function returns true for all rays despite no intersection


By : Annu
Date : March 29 2020, 07:55 AM
wish helps you It seems you got your math a bit mixed. The first part of the function, ie until the first return false, is ok and will return false if the ray start outside of the sphere and don't go toward it. However, I think you put the camera outside all your spheres in such a manner that all spheres are visible, that's why this part never return false.
thcSquared is really wrong and I don't know what it is supposed to represent.
What is the intersection of the keys of dictionaries

What is the intersection of the keys of dictionaries


By : deep aero
Date : March 29 2020, 07:55 AM
wish helps you filter, reduce, map, and lambda... oh my! This is Python, remember, so don't make this harder than it needs to be. Just using a good ol' for-loop:
code :
>>> keys, *morekeys = [d.keys() for d in Ld]
>>> for k in morekeys: 
...     keys &= k 
...
>>> keys
{1, 3}
>>> from functools import reduce
>>> from operator import and_
>>> reduce(and_, [d.keys() for d in Ld])
{1, 3}
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