C++ :: Sorting Of Object In A Vector
Oct 24, 2013
I'm new to C++ especially vectors.. I've a question regarding sorting of object in a vector.. My object consists of x,y and civ. so I would like to know how do I sort the value of the civ in an descending order but at the same time retaining the value of x and y attached to it..
original
X: 4 Y: 5 CIV: 10
X: 3 Y: 2 CIV: 30
X: 3 Y: 3 CIV: 05
sorted
X: 3 Y: 2 CIV: 30
X: 4 Y: 5 CIV: 10
X: 3 Y: 3 CIV: 05
missionplan.cpp
void MissionPlan::topfives() {
stable_sort (topfive.begin(), topfive.end());
pointtwoD = topfive.at(i);
pointtwoD.displayPointdata();
}
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Feb 11, 2012
I'm implementing kruskal's algorithm and ran into some troubles compiling. I need to sort a vector of objects by value. Here is my code and the error I'm getting.
Code:
These are the two functions in graph.cpp (there are more but are unrelated)
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
#include "graph.h"
#include "edge.h"
using std::vector;
void graph::sort_edgesArray() {
[code].....
//This is the error I'm getting.
graph.cpp: In member function "void graph::sort_edgesArray()":
graph.cpp:39:33: error: no matching function for call to sort
(std::vector<edge>::iterator&, std::vector<edge>::iterator&, <unresolved overloaded function type>)
/usr/include/c++/4.5/bits/stl_algo.h:5236:18: note: candidate is:
void std::sort(_RAIter, _RAIter, _Compare)
[with _RAIter = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >, _Compare = bool (graph::*)(edge&, edge&)]
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Oct 30, 2012
Suppose I have a two-dimensional stl vector (a vector of vectors), for example:
Code : vector<vector<int> > x;
And then I want to sort the outer vectors in order of the size of their inner vectors. How do I do this?
Usually, with a one-dimensional vector, I can just create a comparison function and use the sort function. For example, if my vector is defined as:
Code:
vector<int> y;
And I want to sort if in terms of the int values of each vector element, then I can sort by using the stl::sort function, with the comparison function defined as:
Code:
static bool SortFunction(int val1, int val2) {
if (val1 > val2) {
return true;
} else {
return false;
}
};
However, with my two-dimensional vector, I use the following comparison function:
Code:
static bool SortFunction(vector<int> vec1, vector<int> vec2) {
if (vector1.size() > vector2.size()) {
return true;
} else {
return false;
}
};
I get a runtime error:
"Debug Assertion Failed!
File: c:Program Files (x86)Microsoft Visual Studio 10.0VCincludealgorithm
Line 3686
Expression: invalid operator<"
Why is this?
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May 1, 2013
I have a vector of Car* objects - vector<Car*> cars
Each object in the vector has an integer attribute called passengers, which can be returned using the function getPassengers().
How do I sort the vector by the objects' passenger int? I know I need to use sort() and presumably a comparison function but I'm not quite sure how.
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Aug 30, 2014
I'm trying to write a program that reads in from a .txt file the movie title, rating, director, actors etc. All I want to do is to just sort movie titles alphabetically and print all its attributes(director, actors). I tried using sort( movies.begin(), movies.end()) method, but it doesn't work.
here's my code btw:
#include <iostream>
#include <string>
#include <vector>
#include <fstream>
#include <algorithm>
#include <iterator>
#include "Movie.h"
[Code]...
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Jun 26, 2013
writing a sorting function that has an argument for a vector of ints rather than an array; it should use a selection sort algorithm.Here is what I have:
#include <iostream>
#include <vector>
#include <conio.h>
using namespace std;
void fillVector(vector<int> &aVector);
// PRECONDITION: number declared size of array a.
// POSTCONDITION: number_used is the number of values stored in a
//a[0] through a[number_used-1] have been filled with nonnegative int.
[code].....
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Feb 17, 2015
I want to sort a vector int in ascending order, but when I test, the output isn't correct - the vector is still unsorted. Am I calling it incorrectly?
int sorted (vector <int> a) {
int size = a.size();
sort(a.begin(), a.end());
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Dec 1, 2014
I am trying to to pull data from a file into a vector, then calculate different statistics from said vector. I've got everything working great except for one part. The program requires the median be calculated, which means I need to sort the data in the vector. However I can't do a quick easy sort, I'm required to use the functions swap(double, double), sort(vector), and index_of_smallest.
how to get these all working in sync to calculate the median(not to mention my algorithms appear to be wrong as I return nothing but 0's for the median value.)
I'm either not sorting right, or the index_of_smallest function is supposed to be doing something I don't realize.
#include <iostream> // for screen and kbd io
#include <iomanip>
#include <fstream> // file io
#include <cstdlib> // for exit()
#include <cmath> // for sqrt
#include <string>
#include <vector>
using namespace std;
void fill_vector(ifstream& in_file,vector<double>& v);
[code]...
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Nov 2, 2014
I've a vector of objects that I can get my float value from by accessing it through a method.It's not a pointer of vector of objects though.
Meaning it's something like vector[i].getFloatValue().
However,how do I sort the float values by descending order since I access it through a method?
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Aug 25, 2014
I am reading a file and storing the data (all strings) into a vector. How would I sort this alphabetically?
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Oct 26, 2013
I know there is a function in algorithm class called sort() but I need to sort ignoring the case of the alphabet
Is there any function that does that?
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Mar 6, 2014
I am trying to use std::sort to sort a vector of complex objects using a custom function. However, it keeps erroring "Unresolved overloaded function type".
encounter::encounter(){
// ... cut
std::sort (allpeople.begin(), allpeople.end(), sortByInit);}
bool encounter::sortByInit (character& a, character& b) {
if (a.getinit () == b.getinit ()) {
[Code] ....
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Jul 31, 2014
I tried to sort a large numbers of vector of random integers with std::sort(), but when the number increases over 10M, std::sort returns all zero in values. Does std::sort have a limitation of input numbers?
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Aug 7, 2014
I'm trying to use a priority queue sorting in reverse order to take a vector or 2d array. The problem is that I want to sort by the vector/array cell value but keep the reference to the vector/array index of the value. I don't know quite howto keep them both related so when I pop. I can find the corresponding cell.
priority_queue<int, vector<int>, greater<int> > Open;
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Apr 4, 2012
I am erasing a object from the vector. I want to know that do i need to delete the object before I call the erase method or calling the vector erase method is suffice. See the following example.
Class A {
int val;
};
Class B {
vector<A *> vectorA;
void AddA(int val) {
A *a = new A;
a->val = val;
vectorA.push_back(a);
[Code] ....
I don't know which DeleteVectorEntry to use which makes sure that there is no memory leak in my program.
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Jan 28, 2015
I'm working on collision detection for a game in SFML. I successfully designed a Spatial Partition grid to speed up the collision test, in the following of this tutorial: [URL] ....
But now I have an issue with one aspect of it: Going through a vector of objects and testing all the OTHER objects in the vector against said object. The author puts it into psueudocode here:
For each tick of the clock
For every object in the game
Get all the other objects in the same grid square
For each other object in the same grid square
I have trouble with the last line, because in iterating through a vector I am not sure how to skip over the current object. Here is my own code (a couple of sysntax errors but this is a c++ question not an SFML question):
//for every moveable object
for(int i = 0; i < rects_.size(); i++){
std::vector<sf::RectangleShape> posibleObjects_; //this will be a vector of WorldObjects in a real game
//for every object in that object's gridsquare
for(int j = 0; j < rects_.size(); j++){
if(rects_[i].intersects(rects_[j])){
//collision
} } }
The problem is, a collision will always be reported because somewhere in the vector the object will eventually check against itself which is always a true collision. What is the correct way to do this?
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Sep 21, 2013
Here's my code so far:
case DELETE_TITLE:
std::cout << "Game to remove from list: ";
std::cin.ignore();
getline(std::cin, gameTitle);
for (iter = gameList.begin(); iter != gameList.end(); ++iter) {
[code]....
It deletes the text from the string but not the index it self.
It deletes the text but when I print the list of game titles it has it there blank. I want it to completely remove the object from the vector from where it was deleted
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Mar 6, 2013
I want to make a class, named generation, having a vector<chromosome> type data member.
chromosome is also class name.
chromosome has a 'route' as data member, which type is class TArrayI defined in ROOT package.
the size of route is to be fixed according to parameters of generation class object.
class chromosome{
public: chromosome(){;}
....
protected:
TArrayI route;
};
class generation{
public: generation(int PopSize=300, int numCity = 36){
.........
}
vector<chromosome> Population;
};
I want each element, chromosome of Population, to have a numCity size of route.
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Sep 4, 2014
Lets say for example I have the following vector:
vector<Component*> mComponents;
and a function print() inside of class Component that prints the objects name.
How do I loop/iterate through the vector to access the print function in each object.
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Dec 14, 2014
I have this class I have been working with,
Code:
// objects to hold results, row id, and name
class result_holder {
public:
// initialize class members
result_holder() : row_id(0), row_value(0.0), row_name("") { }
[Code] ....
There are cases where I need to find an object based on the value of row_id and delete the object from the vector row_results. I could find the proper object by looping through the vector and testing against each member.
Code:
// id I am looking for
unsigned int id_to_delete = 12;
for(i=0; i<row_results.size(); i++) {
if(id_to_delete == row_results[i].row_id) {
delete row_results[i];
}
}
I have used find before to find the position in a vector with a specific value, but I don't know how to use find to locate a specific value for an object member.
Also, is delete what I need to get rid of the object or should I be using erase as in,
Code:
// id I am looking for
unsigned int id_to_delete = 12;
for(i=0; i<row_results.size(); i++) {
if(id_to_delete == row_results[i].row_id) {
row_results.erase(row_results.begin()+i);
}
}
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Apr 25, 2015
I'm working on a grocery store inventory project. One part is to have a shopping cart, where customers can put in up to 20 items. Because there can be up to 20 shopping carts at one time, I want to use a vector inside the cart object to represent all the individual food items.
Here's my code,
Header:
#ifndef CART_H
#define CART_H
#include <vector>
class Cart {
public:
Cart();
Cart(std::vector< int >, std::vector< int >)
[Code] ....
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Aug 12, 2013
I know what are pointer's and how to use them but there is one point i am not able to understand. Below is the example code
I understand everything in the below code except 1 thing why i am using pointer to base class object in vector int the main() Function?
Code:
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
// base class
[Code] ...
Here is the lines of code i want to understand.
Code:
vector<Employee*> employees;
employees.push_back(&emp1);
employees.push_back(&mgr1);
I know if i will not use the pointer base class function "virtual double grossPay" will be called for both base class object and derived class object and when i will use pointer with reference to the object because base class function is virtual it will look for same function in derived class and if available it will execute it.
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Mar 16, 2013
will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
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Jul 3, 2014
I have a method to take a Tile object and make an instances of it based on some data from the original object. Than it is suppose to manipulate the a specific instance and save the results. The first loop through it works but it changes all instance as well as the base.
public static int recurse(int count, Tile[,] b,Huristic h,int check) {
if (check==1) {
boardState.Add(B)/>;
return check;
} if (check == 0)
[Code] .....
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Dec 13, 2012
#include "B.h"
class A {
public :
A()
{
s_b = new B();
b = new B();
[Code] ....
In my project i have seen static object as above . But not able to know what is the exact use of it and how they are different from general object .
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Sep 11, 2014
a function returns a temporary object like
int myfun(){
int x = 0;
return x;
}
this function will return a temporary integer now void fun1(const int & num); this function can receive from myfun().BUT void fun2(int & num); this function cannot receive from myfun() Why is that, Moreover what is lifetime of a temporary object like one returned in myfun() ???
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