How to insert two or more vector values into another vector without duplicates

Question

Hi Friends,

I have two vectors (values of maps)

map1: (it1)

1=>1  3  5  7

map2: (it2)

3=>1  2  5  8

How to insert these two vectors (I mean the vectors are it1->second and it2->second) into another vector (vector<int>vect) without any duplicate values, That is vect contains 1  3  5  7  2  8?

Answer 1

If vectors are sorted, then consider set_union. An example:

vector<int> v1{ 1, 3, 5, 7 };
vector<int> v2{ 1, 2, 5, 8 };

vector<int> vect;

set_union( v1.cbegin(), v1.cend(), v2.cbegin(), v2.cend(), back_inserter( vect ) );

The result will be sorted too.

To adjust, use it1->second instead of v1 etc.

Answer 2

If vectors are sorted, then consider set_union. An example:

vector<int> v1{ 1, 3, 5, 7 };
vector<int> v2{ 1, 2, 5, 8 };

vector<int> vect;

set_union( v1.cbegin(), v1.cend(), v2.cbegin(), v2.cend(), back_inserter( vect ) );

The result will be sorted too.

To adjust, use it1->second instead of v1 etc.

Well,

If two vectors which could be produced using for() loop.

There is another case we cannot define v2 and it depends on the for() loop results.

Answer 3

Hi Friends,

I have two vectors (values of maps)

map1: (it1)

1=>1  3  5  7

map2: (it2)

3=>1  2  5  8

How to insert these two vectors (I mean the vectors are it1->second and it2->second) into another vector (vector<int>vect) without any duplicate values, That is vect contains 1  3  5  7  2  8?

A simple (but not very efficient) way to do this is to use functions like

void add_distinct(int val, vector<int>& dest)
{
  if (find(dest.begin(), dest.end(), val) == dest.end())
  {
    dest.push_back(val);
  }
}

void add_distinct(const vector<int>& source, vector<int>& dest)
{
  for (size_t i = 0; i < source.size(); i++)
  {
    add_distinct(source[i], dest);
  }
}

Then just insert each original vector to the destination

vector<int> dest;
add_distinct(it1->second, dest);
add_distinct(it2->second, dest);

---

David Wilkinson | Visual C++ MVP

Answer 4

Hi Friends,

I have two vectors (values of maps)

map1: (it1)

1=>1  3  5  7

map2: (it2)

3=>1  2  5  8

How to insert these two vectors (I mean the vectors are it1->second and it2->second) into another vector (vector<int>vect) without any duplicate values, That is vect contains 1  3  5  7  2  8?

A simple (but not very efficient) way to do this is to use functions like

void add_distinct(int val, vector<int>& dest)
{
  if (find(dest.begin(), dest.end(), val) == dest.end())
  {
    dest.push_back(val);
  }
}

void add_distinct(const vector<int>& source, vector<int>& dest)
{
  for (size_t i = 0; i < source.size(); i++)
  {
    add_distinct(source[i], dest);
  }
}

Then just insert each original vector to the destination

vector<int> dest;
add_distinct(it1->second, dest);
add_distinct(it2->second, dest);

---

What is the use of defining two same functions?

Answer 5

A simple (but not very efficient) way to do this is to use functions like

void add_distinct(int val, vector<int>& dest)
{
  if (find(dest.begin(), dest.end(), val) == dest.end())
  {
    dest.push_back(val);
  }
}

void add_distinct(const vector<int>& source, vector<int>& dest)
{
  for (size_t i = 0; i < source.size(); i++)
  {
    add_distinct(source[i], dest);
  }
}

Then just insert each original vector to the destination

vector<int> dest;
add_distinct(it1->second, dest);
add_distinct(it2->second, dest);

---

What is the use of defining two same functions?

Come on Shel88, can you make no effort? The functions are not the same. The first inserts a single value, and the second inserts a vector of values (by calling the first in a loop).

Have you not heard of overloaded functions in C++? If not, you should stop bothering us and go back and start studying C++ from the beginning.

I cannot believe that with any effort at all you could not have understood what the posted code does.

---

David Wilkinson | Visual C++ MVP

Answer 6

If vectors are sorted, then consider set_union. An example:

vector<int> v1{ 1, 3, 5, 7 };
vector<int> v2{ 1, 2, 5, 8 };

vector<int> vect;

set_union( v1.cbegin(), v1.cend(), v2.cbegin(), v2.cend(), back_inserter( vect ) );

The result will be sorted too.

To adjust, use it1->second instead of v1 etc.

Well,

If two vectors which could be produced using for() loop.

There is another case we cannot define v2 and it depends on the for() loop results.

Then also consider an intermediate set:

vector<int> v1{ 1, 7, 5, 3 };
vector<int> v2{ 8, 1, 2, 5 };

set<int> t; // temporary set

// example: insert values from a vector
t.insert( v1.cbegin(), v1.cend() );

// example: insert values by some loop
for( auto i = 0; i < v2.size(); ++i )
{
    t.insert( v2[i] );
}

// build the final vector (if needed instead of set)
vector<int> vect( t.cbegin(), t.cend() );
t.clear();