C++ Tutorial/vector/vector erase

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Erase adjacent duplicates

#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
typedef vector <string> VECTOR_STRINGS;
int main (){
    VECTOR_STRINGS v;
    v.push_back ("A");
    v.push_back ("B");
    v.push_back ("C");
    v.push_back ("D");
    // insert a duplicate into the vector
    v.push_back ("D");
    VECTOR_STRINGS::iterator i;
    // Erase adjacent duplicates
    i = unique (v.begin (), v.end ());
    v.erase (i, v.end ());
    for (size_t nItem = 0; nItem < v.size (); ++ nItem){
        cout << "Name [" << nItem << "] = \"";
        cout << v [nItem] << "\"" << endl;
    }
    return 0;
}

Erase all value in a vector more than three standard deviations greater than the mean

#include <algorithm>
#include <cmath>
#include <functional>
#include <iostream>
#include <list>
#include <numeric>
#include <vector>
using namespace std;
template <class T>
void print(T& c){
   for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
      std::cout << *i << endl;
   }
}
int main( )
{
   const float a[] = { 1, 1.3, 1.5, 0.9, 0.1, 0.2};
   vector<float> data( a,a + sizeof( a ) / sizeof( a[0] ) );
   print( data  );
   float mean = accumulate( data.begin(), data.end(), 0.0f )/ data.size();
   vector<float> zero_mean( data );
   transform( zero_mean.begin(), zero_mean.end(), zero_mean.begin(),bind2nd( minus<float>(), mean ) );
   // compute the sample standard deviation
   float deviation = inner_product( zero_mean.begin(),zero_mean.end(), zero_mean.begin(), 0.0f );
   deviation = sqrt( deviation / ( data.size() - 1 ) );
   // erase all points more than three standard deviations greater than the mean
   const int num_deviations = 3;
   vector<float>::iterator end = remove_if( data.begin(), data.end(), bind2nd( greater<float>(),mean + num_deviations * deviation ) );
   data.erase( end, data.end() );
}

Erase all value in a vector more than three standard deviations less than the mean with erase() remove_if() and bind2nd

#include <algorithm>
#include <cmath>
#include <functional>
#include <iostream>
#include <list>
#include <numeric>
#include <vector>
using namespace std;
template <class T>
void print(T& c){
   for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
      std::cout << *i << endl;
   }
}
int main( )
{
   const float a[] = { 1, 1.3, 1.5, 0.9, 0.1, 0.2};
   // create and initialize vector with above data
   vector<float> data( a,a + sizeof( a ) / sizeof( a[0] ) );
   cout << "DATA VECTOR HAS " << data.size() << " ELEMENTS\n";
   print( data  );
   // compute the mean
   float mean = accumulate( data.begin(), data.end(), 0.0f )/ data.size();
   // subtract the mean from every data point
   vector<float> zero_mean( data );
   transform( zero_mean.begin(), zero_mean.end(), zero_mean.begin(),bind2nd( minus<float>(), mean ) );
   // compute the sample standard deviation
   float deviation = inner_product( zero_mean.begin(),zero_mean.end(), zero_mean.begin(), 0.0f );
   deviation = sqrt( deviation / ( data.size() - 1 ) );
   const int num_deviations = 3;
   // erase all points more than three standard deviations less than the mean
   data.erase( remove_if( data.begin(), data.end(),bind2nd( less<float>(), mean - num_deviations * deviation ) ),data.end() );
}

Erase first element

#include <iostream>
using std::cout;
using std::endl;
#include <vector>    // vector class-template definition
#include <algorithm> // copy algorithm
#include <iterator>  // ostream_iterator iterator
#include <stdexcept> // out_of_range exception
int main()
{
   int array[ 6 ] = { 1, 2, 3, 4, 5, 6 };
   std::vector< int > integers( array, array + 6 );
   std::ostream_iterator< int > output( cout, " " );
   integers.push_back( 2 );
   integers.push_back( 3 );
   integers.push_back( 4 );
   cout << "Vector integers contains: ";
   std::copy( integers.begin(), integers.end(), output );
   // erase first element
   integers.erase( integers.begin() );
   cout << "\n\nVector integers after erasing first element: ";
   std::copy( integers.begin(), integers.end(), output );

   return 0;
}
Vector integers contains: 1 2 3 4 5 6 2 3 4
Vector integers after erasing first element: 2 3 4 5 6 2 3 4

erase the numbers 2 through 5 in v1

#include <vector>
#include <algorithm>
#include <iterator>
#include <iostream>
using namespace std;
void printVector(const vector<int>& v){
  copy(v.begin(), v.end(), ostream_iterator<int>(cout, " "));
  cout << endl;
}
int main(int argc, char** argv){
  vector<int> v1, v2;
  int i;
  v1.push_back(1);
  v1.push_back(2);
  v1.push_back(3);
  v1.push_back(5);
  v1.insert(v1.begin() + 3, 4);
  // Add elements 6 through 10 to v2
  for (i = 6; i <= 10; i++) {
    v2.push_back(i);
  }
  printVector(v1);
  printVector(v2);
  // add all the elements from v2 to the end of v1
  v1.insert(v1.end(), v2.begin(), v2.end());
  printVector(v1);
  // erase the numbers 2 through 5 in v1
  v1.erase(v1.begin() + 1, v1.begin() + 5);
  printVector(v1);
  printVector(v2);
  return (0);
}

insert and erase.

#include <iostream>
#include <vector>
using namespace std;
   
int main()
{
  vector<char> v(10);
  vector<char> v2;
  char str[] = "<Vector>";
  unsigned int i;
   
  for(i=0; i<10; i++) v[i] = i + "a";
   
  // copy characters in str into v2
  for(i=0; str[i]; i++) 
     v2.push_back(str[i]);
 
  // display original contents of vector
  cout << "Original contents of v:\n";
  for(i=0; i<v.size(); i++) cout << v[i] << " ";
  cout << "\n\n";
   
  vector<char>::iterator p = v.begin();
  p += 2; // point to 3rd element
   
  // insert 10 X"s into v
  v.insert(p, 10, "X");
   
  // display contents after insertion
  cout << "Size after inserting X"s = " << v.size() << endl;
  cout << "Contents after insert:\n";
  for(i=0; i<v.size(); i++) cout << v[i] << " ";
  cout << "\n\n";
   
  // remove those elements
  p = v.begin();
  p += 2; // point to 3rd element
  v.erase(p, p+10); // remove next 10 elements
   
  // display contents after deletion
  cout << "Size after erase = " << v.size() << endl;
  cout << "Contents after erase:\n";
  for(i=0; i<v.size(); i++) cout << v[i] << " ";
  cout << "\n\n";
   
  // Insert v2 into v
  v.insert(p, v2.begin(), v2.end());
  cout << "Size after v2"s insertion = ";
  cout << v.size() << endl;
  cout << "Contents after insert:\n";
  for(i=0; i<v.size(); i++) cout << v[i] << " ";
  cout << endl;
   
  return 0;
}

Remove(delete) all elements in the vector

#include <iostream>
using std::cout;
using std::endl;
#include <vector>    // vector class-template definition
#include <algorithm> // copy algorithm
#include <iterator>  // ostream_iterator iterator
#include <stdexcept> // out_of_range exception
int main()
{
   int array[ 6 ] = { 1, 2, 3, 4, 5, 6 };
   std::vector< int > integers( array, array + 6 );
   std::ostream_iterator< int > output( cout, " " );
   integers.push_back( 2 );
   integers.push_back( 3 );
   integers.push_back( 4 );
   cout << "Vector integers contains: ";
   std::copy( integers.begin(), integers.end(), output );
   // erase remaining elements
   integers.erase( integers.begin(), integers.end() );
   cout << "\nAfter erasing all elements, vector integers "
      << ( integers.empty() ? "is" : "is not" ) << " empty";
   return 0;
}
Vector integers contains: 1 2 3 4 5 6 2 3 4
After erasing all elements, vector integers is empty

Use unique_copy to remove duplicate words

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
    vector<string> coll;
    /* read all words from the standard input
     * - source: all strings until end-of-file (or error)
     * - destination: coll (inserting)
     */
    copy (istream_iterator<string>(cin),    // start of source
          istream_iterator<string>(),       // end of source
          back_inserter(coll));             // destination
    // sort elements
    sort (coll.begin(), coll.end());
    /* print all elements without duplicates
     * - source: coll
     * - destination: standard output (with newline between elements)
     */
    unique_copy (coll.begin(), coll.end(),             // source
                 ostream_iterator<string>(cout,"\n")); // destination
}
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