C++ :: Sort / Find Duplicates And Remove From Vector
Nov 18, 2013
I'm trying to sort my vector, find duplicate values using unique and erase them. Program can compile successfully but the duplicates are not removed.
output:
x: 3
y: 2
x: 6
y: 4
x: 3
y: 2
vector<Point2D> p2dvector;
void readData()
[Code].....
I also have operator== in my Point2D class which I understand it is required to use unique for vector.
bool operator==(const Point2D& lhs, const Point2D& rhs)
{
return lhs.x == rhs.y;
}
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Mar 18, 2014
I have a vector of
strings.vector input;
bob
sam
bob
sammom
aardvark
money
aardvark
wanted
I need to remove the duplicates but each part of the vector corresponds to the next location. They are pairs.
ex. bob corresponds to the its definition, which is sam.
I need to keep the first instance, so keep bob and sam, but remove the second instance of bob, so remove bob and sammon. Only the first instance of the pair need to kept.
It doesn't matter if the sam and sammon don't match, all that matters is the first part of the pair.
The vector is already in alphabetical order. I can't use the algorithm library.
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Apr 3, 2013
Code: /*
generals is the first array. Max 10 elements.
numGenerals is the element count of generals.
genBuff is the second array; it is to be checked/pruned.
genCount is the element count of genBuff.
genBuff will be a max of 171, but be pruned to no more than 10, and no more than the complement of the element count of generals.
*/
[Code] ....
(I do have comments in the actual source, different from above).
I have two int arrays. They hold values from 0 to 170. The first one will never be more than 10. The second will be at most 171, but will be whittled down to at most 10, usually less. 171 is worst case, most users of this particular program will probably be reasonable and not try to add all 171 (max is 10 anyway). The first array is the original array. The second array is a temporary array. Any value in the second array that is also found in the first array, is removed from the second array, since all values in the first one must be unique. After this pruning process, both arrays will collectively contain no more than 10 unique elements; the elements from the second will be added to the first.
So right now I have three nested loops. I figured with the miniscule array sizes it wouldn't be a big deal. I can think of a way to remove one or two of them, but I want to be sure that I'm still writing clean, legible, good-practice code. The first loop walks through the first array. For each element in the first array, there is a second loop to walk through the second array to check for duplicates. If a duplicate is found, the third loop walks through the second array to overwrite the duplicate while preserving the second loop's position (j).
Is this dumb? I know that the big O gets worse and worse the deeper you go with nested loops. Even though the arrays are really tiny, is this still a thing to avoid?
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Aug 25, 2014
I have this structures:
Code:
typedef struct {{
GList *presets;
} Settings;
typedef struct Preset preset;
struct Preset
{gchar *name;
[Code]...
I want to remove duplicates items in list if them have same freq value.
Example output with duplicate freq:
PHP Code:
name freq unammed 87.80 Radio ZU 92.20 Napoca FM 104.50 unammed 92.20 Rock FM 102.20
Want output:
PHP Code: Europa FM 92.20 unammed 87.80 Radio ZU 92.20 Napoca FM 104.50 Rock FM 102.20
write code to remove duplicates.
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Jul 21, 2014
I have an array of structures with structure def that looks like.
Code:
struct {
char * name;
char * school;
int age;
}
there are multiple people with same name but different ages so i want to list them like.
Name.
age 1
age 2 and so on
The array is sorted by name already.
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Mar 8, 2013
I have a text file that needs to be read by command line arguments. The text are all numbers and can have multiple numbers on one line separated by a space. I cannot use an array or sort the numbers.So say I have a text file, listNums.txt:
12
473 8 29
30 1
8
248 17 55
29 84
5
Basically I need to read one number, find out if its odd or even by dividing by 2, search the odd or even doubly linked list that it would go into to see if its in there, if its not then add it to the bottom of the list.
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Dec 1, 2014
I have vector pair like below, it is sorted but I want to remove duplicate values: The vector is like below:
std::vector<std:air<std::string,double>> fileWeight;
Here is what in vector:
scene1.jpg 0.4
scene2.png 0.4
scene3.jpg 2.3
scene4.jpg 4.1
The highlighted top 2 are duplciated. How can I remove duplciated like this where I have to check whole pair?
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Sep 22, 2014
pop_back just returns void, so I just can't use that?
erase is okay but it doesn't return anything....
Do I use a combination of both?
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Dec 8, 2014
I have a vector of int,
Code:
vector<int> row_numbers{1,2,3,4,5,6,7,8,9};
I want to sequentially remove one element at a time starting with the first. When the second element is removed, the first element needs to go back in. The sequence would look like
Code:
// original vector, row_numbers.size()=9
row_numbers{1,2,3,4,5,6,7,8,9};
// trimmed vector, row_numbers_trim.size()=8
[Code] .......
I have been working under the assumption that the best method would be to have row_numbers remain untouched and work on a copy. For each step in the sequence, you would create row_numbers_trim as a copy of row_numbers, and then remove an element from row_numbers_trim.
Code:
// position being removed
int counter = 0;
// copy original vector
row_numbers_trim = row_numbers;
// remove the first element from the copy
row_numbers_trim(row_numbers_trim.begin()+counter);
All you would have to do here is to increment counter in a loop. is there a better way?
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Jul 5, 2013
I have asked a related question before, and it was resolved successfully. In the past, when I wanted to use std::max_element in order to find the maximum element (or even sort by using std::sort) of a vector of structures according to one of the members of the structure, all I had to do was to insert a specially designed comparison function as the third argument of the function std::max::element. But the latter comparison function naturally accepts two arguments internally.
For instance, here is a test program that successfully finds the maximum according to just one member of the structure:
Code:
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
[Code] ....
And the output was this, as expected:
Maximum element S.a of vector<S> vec is at: 9
[I]max element of vec.a between slot 3 and slot 6 is: 6, and its index is: 6 vec[6].a = 6
[I]max element of vec.a between slot 4 and slot 7 is: 7, and its index is: 7 vec[7].a = 7
[I]max element of vec.a between slot 5 and slot 8 is: 8, and its index is: 8 vec[8].a = 8
[I]max element of vec.a between slot 6 and slot 9 is: 9, and its index is: 9 vec[9].a = 9
However, I now need to search and find an element of vector<myStruct> according to just one member of myStruct, instead of finding the maximum or sorting as before. This presents a problem because the function std::find does not accept such a comparison function as its third argument.
This was the description of the std::find function that I found: find - C++ Reference
Code:
template <class InputIterator, class T> InputIterator find (InputIterator first, InputIterator last, const T& val);
I could also find another function called std::find_if, but this only accepts a unary predicate like this: find_if - C++ Reference
Code:
template <class InputIterator, class UnaryPredicate> InputIterator find_if (InputIterator first, InputIterator last, UnaryPredicate pred);
And once again this is either inadequate of I don't see how to use it directly, because for the third argument I would like to insert a function that takes two arguments with a syntax like this:
Code:
int x=7;
std::vector<S>::iterator result;
result = std::find(vec.begin(), vec.end(), []( const (int x, const S & S_1) { return ( x == S_1.a ) ; } ) ;
Is there another std function that I can use to make search and find an element according to just one member of myStruct?
Or perhaps there is a clever way to pass two arguments to the unary predicate.
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Feb 23, 2014
I'm working on a code for ascertaining the minimum penalty of an assignment problem. The basic complication of my code is this: I have a vector of objects of a custom struct. The struct has a member, which is an integer. I need to keep the vector sorted according to that member, even when objects are added to or deleted from the vector. To illustrate the problem, I'll give an example.
Code:
typedef struct examplestruct{int i;
char c;
...} es;
int function(void)
{vector<es> ObjectTable;
//insert an object so that the vector remains sorted according to i
insertobject( newobject, &ObjectTable);
//deleting the top element of the vector
deleteobject(&ObjectTable);
return 0;}
I have tried to do it using bubblesort. But it's too slow. How to make a heap out of it.
The detailed premises of the problem is this: There are a number of jobs, and with each job a completion time and a cost coefficient. We are to ascertain the optimal sequence of jobs for which the penalty is minimum. Now, suppose we are given jobs A, B, C, D and E. We find out the lower bound of penalties for all the jobs.
Suppose we find B has the lowest penalty. Then we find out the lower bound of penalties for BA, BC, BD and BE. We continue this until we have the best value and a complete sequence. The way I have implemented this in a code: I have created two structs. One is Job, with the completion time and cost coefficient as members. The other is Node. Nodes have a Job Array and a Penalty as members. Now, we have a vector of Nodes which we need to keep sorted according to the penalty. We need to insert new Nodes and delete the expanded Nodes.
I have included my code. The pushInTable function inserts the new Nodes in a sorted vector. But it slows down remarkably when we give more than 20 jobs as input.
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Nov 5, 2014
Im creating a program for a race. The Race class has a vector of results and each element of that vector is a pointer to a result. The Result class has a Time and a pointer to a Participant. So in each race there are various results and it is a result for each participant.The Time is a class that has hours, minutes and seconds. How can I sort the vector of results from the result of the participant with the fastest time to the result of the participant with the slowest time?My code is like this:
//.h file:
class Time {
unsigned int hours;
unsigned int minutes;
unsigned int seconds;
[code]....
What am I missing to get my code to work?
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Aug 5, 2014
I'm trying to sort by age a vector of birthday dates. I'm using the functions in the <ctime> header to calculate the difference in seconds between two date but it doesn't work! If I try to print 2 different dates with asctime() or ctime() it either prints 2 time the same date or throws an exception! I post my code below: p.s.: I'm using a wrapper class called Date.
#include <ctime>
#include <iostream>
#include <conio.h>
[Code].....
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Nov 5, 2014
Im creating a program for a race. The Race class has a vector of results and each element of that vector is a pointer to a result. The Result class has a Time and a pointer to a Participant. So in each race there are various results and it is a result for each participant. The Time is a class that has hours, minutes and seconds. How can I sort the vector of results from the result of the participant with the fastest time to the result of the participant with the slowest time?
Im getting some errors in my code. I put the error as comments in the code. Each error is after the line where it occurs. My code is like this:
//.h file:
class Time
{
unsigned int hours;
[Code]....
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Dec 10, 2014
I have a small class and a vector to hold the objects.
Code:
class result_holder {
public:
// initialize class members
[Code]....
The purpose is to keep results and be able to sort the results on row_value while keeping the id and name values in registration with the row_value. I am running allot of tests and keeping the top n results. The idea is to sort the vector so that I can just examine the object in the last element to see if it should be replaced by a better result.
I know that this kind of thing is often done with an overloaded operator or a functor, but I am a bit out of my depth with that, especially determining what class variable will be used for the sort. sorting the above objects on the row_value variable?
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Aug 10, 2013
For example let say there is vector [1,2,3,4,5,6,7,8,9] and let say there is int n
if i say n=3
I want to find all possible 3 combination
[1,2,3][1,2,4].....such and such
if i say n=4
[1,2,3,4][1,2,3,5]......
I want to know how you write the code depend on the input n. Is it call dynamic programming?
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Oct 15, 2013
So the program reads contents from a text file into a vector and then the user enters in a string that they want to search for. The program iterates through the vector to find the string and then saves that line to another vector to display later(incase there is more then 1 instance of the string found).
Here is what I have atm:
void doSearch(vector<string> &phonelist, string searcher, vector<string> &holdNumbers)
{
int i = 0;
string value;
[Code].....
I just get an R6010 error -abort() has been called.
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Feb 16, 2015
Im currently trying to find the mode of a vector through a map but am not sure how to do so besides the attempt ive made
void mode(vector<double>v)
{
map<double, int> map;
[Code]....
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Jul 21, 2013
Ok my assignment has me doing vector math with some canned code provided for me by the instructor This is the header file to the class I'm working with and the .cpp file as far as I've gotten it.
#pragma once
#include "Scalar.h"
class Vector2D {
public:
Vector2D();
Vector2D( const Vector2D& ) ;// copy constructor
Vector2D( Scalar element[2] ) ; // initialize with an array
[Code] ....
I'm having trouble seeing which data members I'm multiplying together and what the initial state, continuing state, and after loop action I'm supposed to be using in the for loop.
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Sep 4, 2013
I defined the following function to find out the iterator of a certain value in the vector. I defined it as such so if the value exist in the vector then return a iterator of it, if not then return a pointer pointing to nonsense.:
vector<tIndex_t>::iterator unlabelTit(const tIndex_t index) {
for(vector<tIndex_t>::iterator it=unlabelT.begin(); it<unlabelT.end(); it++) {
if(index==*it) return it;
} return NULL;
}
But looks this one is not accepted by compiler, saying I cannot do this kind of comparison like:
unlabelTit(i)!=NULL;
so I just delete the return NULL; and then the compiler giving me warning about no return statement before }.
a pointer pointing to nonsense? how to do that?
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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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Oct 12, 2014
Okay, so for an assignment I need to write a function called find() that returns a reference to a vector. So I have vector <int> & find(string & key); If I do this, I get the obvious warning warning: reference to local variable 'lineNum' returned [enabled by default].
If I do vector<int> & find(string & key) const; I get a huge error that starts out like
In member function 'std::vector<int>& index_table::find(std::string&) const':
indextable.cpp:74:30: error: no match for 'operator='
Am I using the const identifier incorrectly?
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Dec 31, 2012
I want to build a server which holds hundreds of thousands of active users in memory. To keep all the users organized i would like to store them in a Vector.
The problem is how i could quickly and easy find the object whenever i need it? All users will have a unique ID. Would it be possible to keep some form of a Vector Index on the unique id number?
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Mar 4, 2015
This program is to solve a word maze and find the number of words in the maze from a dictionary file.
The program runs, but stops by finding 1,2 and 3 letter words.
#include<iostream>
#include<vector>
#include<fstream>
#include<algorithm>
#include<string>
using namespace std;
int main() {
vector <string> dict,forward,reverse;
[Code] .....
I also tried to find words using the entire vector as a container, the synopsis code that also did not work is below
while(j<dict.size()) {
if(dict[j].size()>2) {
if (std::find(forward.begin(), forward.end(), dict[j]) != forward.end()) {
cout<<"found word "<<dict[j]<<endl;
[Code] ....
Attached File(s)
dumpling2.txt (2.54K)
Dictionary.txt (718.34K)
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Oct 13, 2014
Lets say that i have the coordinates of a 2D space (x and y), I want to store the coordinates as x and y in a vector to find the nearest neighbor of given points like i have:
#3.57 3.18#
#84.91 27.69
#93.40 4.62
#67.87 9.71
#75.77 82.35
#74.31 69.48
#39.22 31.71
#65.55 95.02
#17.12 3.44
#70.60 43.87
Each coordinates is like x y and it shows points 1 to 10 (like 3.57 3.18 is point 1 in 2D space ). My question is that how i add all x and y coordinates in vector? I started like this;
`struct point{
int x;
int y;
[Code] ....
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Feb 24, 2013
I am having problems with this function:
bool HashTable::insert(char const * const key, const Player& aPlayer) {
//calculate the insertion position (the index of the array)
size_t index = calculateIndex(key);
for(int i=0; i < capacity; i++) {
[Code] ....
The inserting part works just fine, but the checking for duplicates where I compare the two values is crashing my program.
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