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[Skyrunner]

Ohh, right, quad/octrees work for n-body simulations because those only need "good enough" approximations...

[monkey]

What would be the best method for finding which point from an array is the closest to a chosen point in an N dimension space (where N is a large number), if there are a lot of points and I can't afford to simply loop through all of them?

If you need to find several points using with the same array, it might be worth it to build a tree (quadtree / octree or kd-tree)
It might be cheaper to just check all of them, easy to parallelize or even send it to a gpu ?

[cerapa]

What would be the best method for finding which point from an array is the closest to a chosen point in an N dimension space (where N is a large number), if there are a lot of points and I can't afford to simply loop through all of them?

Never forget that you don't need the actual distance, only the closest point(you can do the actual distance later if you need it), so there is no need for square roots or its ilk.

[Reelya]

no need for square roots per point at all. you just do distance^2 which is faster. then a single square root for the final chosen point.

[Spehss _]

Anyone know how to print non char or string variables onto a screen in curses? I'm using pdcurses in c++. Seems like all the print commands for curses only take strings/characters, so if I wanted to print, say, the value of an int onto the curses window, the print commands won't take the variable itself.

So I guess I'd need a way for the program to take the int variable, make a char variable of the number, and use that variable. Like, if int X is 3, the program takes X and makes a char variable that is '3' for printing.

I'm stumped.

[Putnam]

In C++11, std::tostring(num) is apparently a thing.

[Spehss _]

Spoiler: errorlog (click to show/hide)

Code: [Select]

"to_string" was not declared in this scope

googling "c++ tostring" brings up "to_string". Neither works.

[cerapa]

std::to_string(whatever)

Should be included with just strings in general coming from any random included thing, but you can try adding #include <string> if it doesn't work.

[Spehss _]

Tried that too. Still doesn't work. "not declared in this scope".

Spoiler: code so far (click to show/hide)

Code: [Select]

#include <iostream>
#include <string>
#include <stdlib.h>             //srand, rand
#include <stdio.h>              //printf, null
#include <time.h>               //time for srand and rand seed
#include <vector>               //vectors
#include "pdc34dllw/curses.h"   //curses

using namespace std;

int flipCoin(int coinNum)
{
    int result=0;
    for(int i=0; i<coinNum; i++)
    {
        int flip=((rand()%2)+1);
        if(flip==2)         //heads=2
        {
            result+=1;      //if heads, get 1 coin
        }
        else if(flip==1)    //tails=1
        {
            result-=1;      //if tails, lose 1 coin
        }
    }
    return result;
}

int main()
{
    int coinTotal=1;
    int d6Total=1;
    initscr();
    printw("You have");
    printw(to_string(coinTotal));
    printw(" coins & ");
    printw(to_string(d6Total));
    printw(" dice.");
    refresh();
    getch();
    endwin();

    return 0;
}


[cerapa]

Are you sure you have C++11 enabled? What IDE and compiler are you using?

[Spehss _]

Are you sure you have C++11 enabled? What IDE and compiler are you using?

IDE==Code::Blocks and compiler==GNU GCC compiler. I set it to use c++11 after someone mentioned it during an earlier question I had. I checked earlier, the option is still checked.

[cerapa]

Strange. I have the same IDE and compiler.

Can you use other c++11 features? Like...range based loops for example?

Code: [Select]

int my_array[5] = {1, 2, 3, 4, 5};

for (int &x : my_array) {
    x += 1;
}

[Spehss _]

Strange. I have the same IDE and compiler.

Can you use other c++11 features? Like...range based loops for example?

Spoiler (click to show/hide)

Code: [Select]

int my_array[5] = {1, 2, 3, 4, 5};

for (int &x : my_array) {
    x += 1;
}

Yeah, that compiled ok.

[cerapa]

I distinctly remember having a similar issue with to_string at some point, but that might have just been because I didn't have c++11 turned on.

Meanwhile you can convert numbers to string through a stream. Less convenient than to_string, but you gotta do what you gotta do.

Code: [Select]

#include <sstream>

stringstream streamofstrings;
streamofstrings << yourint;
resultingstring = streamofstrings.str();
String doesn't look like a word anymore.

[Gentlefish]

@spehss

Simple solution! Make a function that feeds a string, character-by-character into the curses print function.

It's not pretty, it's not optimized, but it'll damn well work.