sort a Map based on value

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Hi all,

Can anybody tell me how to sort a map based on the values.
e.g.

Map[key1] = box3;
Map[key2] = box1;
Map[key3] = box4;
Map[key4] = box2;

i want result like,

Map[key2] = box1;
Map[key4] = box2;
Map[key1] = box3;
Map[key3] = box4;

thanks in advance,
RKR

Posted 25-Jun-12 23:01pm

NajaR12

Updated 25-Jun-12 23:13pm

Prasad_Kulkarni

v2

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[no name] 26-Jun-12 5:10am

How is the map declared?

Jim Jos 26-Jun-12 5:50am

MAP is a sorted container and not sure why you want to sort a map on values.. Could you tell me your requirement and we ll be figure out the right data structure for you..

NajaR12 26-Jun-12 6:18am

Map declaration is as below
map<int, string=""> myMap;

Now Map is sorted based on key but i want to sort based on the value i.e string.

Chandrasekharan P 26-Jun-12 6:22am

Please don't cross post your questions.

ThatsAlok 27-Jun-12 2:47am

and what benefits will you get getting sorted data on the base of value. Key will definatly lose it significance!

2 solutions

Solution 1

Provide of a container with the type of the key, and populate the container in the sort order of the values in the map. Thus, you can access the sorted values via the sorted key container. However, you will need to update and resort the key container whenever you modify the map container.

An alternative would be to populate a multipmap container where the values of the map<key_type, val_type> become keys, and the keys become values: multimap<val_type, key_type>.

Posted 26-Jun-12 1:15am

George L. Jackson

Updated 26-Jun-12 2:49am

v2

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**ThatsAlok** · Accepted Answer · 2012-06-26T20:51:00

Solution 2

I doubt stl::map can help you in above, you asking it to break it basic principle. I believe you have write your own custom data structure for this.

Also, what actually you going to achieve to sort it on the basis of value? if you are going to iterate one by one instead of finding data based on key, better look for other container instead of map

Posted 26-Jun-12 20:51pm

ThatsAlok

Updated 26-Jun-12 20:52pm

v2

Comments

NajaR12 29-Jun-12 7:40am

Thanks for the reply.
Actually key was not significant for me. I used List instead of Map then used the sort() method. my job is done :)