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Does set<vector<int> > have to define compare function?


Does set<vector<int> > have to define compare function?

By : YupYesYeah
Date : November 17 2020, 11:52 AM
wish helps you std::less will just invoke operator< on the T objects, unless it is specialized. std::vector has operator< defined, which gives a lexicographic comparison of the elements.
code :


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Compare class vector's two function returns with other class vector elements functions

Compare class vector's two function returns with other class vector elements functions


By : bar1004
Date : March 29 2020, 07:55 AM
Does that help To remove duplicates, you can first sort the vector with std::sort and then use std::unique to remove the duplicates. If the duplicates are already in consecutive elements, you can skip std::sort and just use std::unique.
To make these work, you need to tell them how to compare the elements.
code :
bool less_name_age( MyClass const &lhs, MyClass const &rhs ) {
    return lhs.name < rhs.name? true // ascending alphabetical names
         : rhs.name < lhs.name? false
         : lhs.age < rhs.age? true // ascending ages
         : rhs.age < lhs.age? false
         : rhs.id < lhs.id; // descending order of ID
}

bool equal_name_age( MyClass const &lhs, MyClass const &rhs ) {
    return lhs.name == rhs.name && lhs.age == rhs.age;
}

std::sort( vec.begin(), vec.end(), less_name_age );
std::vector< MyClass >::iterator new_end
    = std::unique( vec.begin(), vec.end(), equal_name_age );
define set compare function when set is the element of a vector

define set compare function when set is the element of a vector


By : Ashwini g.n
Date : March 29 2020, 07:55 AM
With these it helps You probably don't assign isSmall as comparator. (The template argument just specifies the type of it)
code :
using T = std::pair<int, int>;

bool isSmall(T const & i1, T const & i2)
{
    return i1.second < i2.second;
}

void main()
{
    typedef bool(*CompareFunc)(T const &, T const &); // decltype(isSmall)*

    std::vector< std::set<T, CompareFunc> > vec_set;

    vec_set.push_back(std::set<T, CompareFunc>(isSmall)); // <-- assign the function in every set<>-constructor manually
    vec_set[0].insert({ 1,1 });
    vec_set[0].insert({ 1,1 });
}
struct CompareFunc // : public std::binary_function<T, T, bool>
{
    bool operator()(T const &i1, T const &i2) const
    {
        return i1.second < i2.second;
    }
};

void main()
{
    std::vector< std::set<T, CompareFunc> > vec_set;

    vec_set.resize(1); // <-- comparator gets instantiated automatically
    vec_set[0].insert({ 1,1 });
    vec_set[0].insert({ 1,1 });
}
MATLAB does not define vector for a specific function when I use a vector as an input

MATLAB does not define vector for a specific function when I use a vector as an input


By : Csaba Selmeczi
Date : March 29 2020, 07:55 AM
around this issue Considering that the other variables are scalars, and only V is a vector, I think you forgot a dot before the division.
Gacc=(V.^2)./(g*L+Kus*V.^2)
How to define a vector function

How to define a vector function


By : craig23
Date : March 29 2020, 07:55 AM
it fixes the issue I want to define a vector function in x like this [sin(x),sin(2*x), ... ,sin(100*x)] where x is a variable. What I defined is that : , Method 1, use vectorization (simplest, fastest):
code :
H=@(N,x) sin((1:N)'.*x);
%With the '.*' operation u can create the full matrix in single call:
N=100; 
x=0:0.01:pi;
M=H(N, x)
N=10;
H=@(x) arrayfun(@(i)sin(i*x),1:N);
I have defined a vector according to a certain rule. How do I define a function that outputs the vector?

I have defined a vector according to a certain rule. How do I define a function that outputs the vector?


By : John Knecht
Date : March 29 2020, 07:55 AM
To fix the issue you can do Generating values is elegantly done using the apply family of functions. vapply is lesser known, but more efficient than sapply, so I promote it here. The numeric(1) specifies what the result of f is expected to be:
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