How to put one QMap into another QMap

Question

Project should give as random number but that is not important, then that number of random find in first map and add into second map.

int rand = 2;
QPixmap pixmap1 = QPixmap (":/imag/sedam_one.jpg");
QPixmap pixmap2 = QPixmap (":/imag/gedam_one.jpg");
QPixmap pixmap3 = QPixmap (":/imag/tedam_one.jpg");
QMap<int, QPixmap> map;
map.insert(1, pixmap1);
map.insert(2, pixmap2);
map.insert(3, pixmap3);
QMap<int, QPixmap> myMap;
myMap.insert(map.key(rand), map.value(rand));

Do you want to take key-value pairs randomly from one map and then put them into another? Is that your question? — mhcuervo, Sep 02 '14 at 20:36
What about `myMap.insert(rand, map.take(rand))` ? -> Providing that you make sure rand is a valid key first. — mhcuervo, Sep 02 '14 at 20:54

score 0 · Answer 1 · answered Sep 02 '14 at 21:02

0

Your code will be different based on the behavior you want when rand is not a valid key.

If you want to ignore the key if it is not there in map, you would use:

if ( map.find(rand) != map.end() )
{
  myMap.insert(map.key(rand), map.value(rand));
}

If you want a default-constructed value when the key is not there map, you would not create the if check from the above code and simply use the code that you have:
```
myMap.insert(map.key(rand), map.value(rand));
```

answered Sep 02 '14 at 21:02

R Sahu

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@mario, if you think your solution will be useful to SO, please post it as an answer. Otherwise, delete your question. – R Sahu Sep 03 '14 at 15:15

score 0 · Answer 2 · answered Apr 24 '16 at 02:50

Here's one way to do that:

  int rand = 2;
 QPixmap pixmap1 = QPixmap (":/imag/sedam_one.jpg");
 QPixmap pixmap2 = QPixmap (":/imag/gedam_one.jpg");
 QPixmap pixmap3 = QPixmap (":/imag/tedam_one.jpg");
 QMap<int, QPixmap> map;
 map.insert(1, pixmap1);
 map.insert(2, pixmap2);
 map.insert(3, pixmap3);
 QMap<int, QPixmap> myMap;
 myMap.insert(rand, map.value(rand));

Notice the last line. map.key(rand) should be just rand because the method map.key() requires that you put in a value such as a QPixmap

score 0 · Answer 3 · answered Apr 17 '23 at 05:58

Warning: This will overwrite values. You can use a QMultiMap if you wish to have multiple keys.

QMap<QString,QString> sneed;
QMap<QString,QString> feed;

QMapIterator<QString,QString> i_Map(feed);
while ( i_Map.hasNext() ) {
        i_Map.next();
        sneed.insert( i_Map.key(), i_Map.value() );
}

How to put one QMap into another QMap

3 Answers3