Delete duplicate elements in vector

[flavourofbru]

Hi,

vector<string> str;

I have the vector filled with strings "a", "b", "c", "b", "c", "d", "a".
i.e
str[0] = a; str[1] = b; str[2] = c;.....and so on.

Now I would like to delete the duplicate elements in the above vector such that the vector only contains distinct elemets "a", "b", "c" and "d".

How can I do that??

Please help

Thanks!!

[sicarie]

Hi,

vector<string> str;

I have the vector filled with strings "a", "b", "c", "b", "c", "d", "a".
i.e
str[0] = a; str[1] = b; str[2] = c;.....and so on.

Now I would like to delete the duplicate elements in the above vector such that the vector only contains distinct elemets "a", "b", "c" and "d".

How can I do that??

Please help

Thanks!!

I would recommend using a second vector and a for loop to iterate through the elements (vector iterator). Then you can compare the current vector against all the elements of the second vector. Does that make sense, or do I need to get into a bit more detail?

[forumsaregreat]

Hi,

vector<string> str;

I have the vector filled with strings "a", "b", "c", "b", "c", "d", "a".
i.e
str[0] = a; str[1] = b; str[2] = c;.....and so on.

Now I would like to delete the duplicate elements in the above vector such that the vector only contains distinct elemets "a", "b", "c" and "d".

How can I do that??

Please help

Thanks!!

Do you really need a vector ??
If you have to eliminate duplicates then using a set is most useful as every element is added only once.

/ Sid

[flavourofbru]

Hi Sicarie,

Can you please give me more details on what you have said, as I am not able to exactly grasp what you meant.

I have a large set of code where I have been using vectors, so now I will not be able to switch from vectors to sets.

What is the possible way to achieve this using vectors??

Thanks!!

[sicarie]

Hi,

vector<string> str;

I have the vector filled with strings "a", "b", "c", "b", "c", "d", "a".
i.e
str[0] = a; str[1] = b; str[2] = c;.....and so on.

Now I would like to delete the duplicate elements in the above vector such that the vector only contains distinct elemets "a", "b", "c" and "d".

How can I do that??

Please help

Thanks!!

my algorithm would probably look something like this

vector str
vector str_noDuplicates
str Iterator
element_str
element_strNoDuplicates
 
for each element in str
    element_str = next element
    for each element in str_noDuplicates
        element_strNoDuplicates = next element
        if element_str == element_strNoDuplicates
            set duplicateFlag to true
        end if
    end for
    if duplicateFlag == false
        add element_strNoDuplicates to str_noDuplicates
    else
        do nothing
end for
 

Does that help?

[RRick]

This is where the builtin STL functions come in handy.

First you sort the array and then use unique to remove adjacent duplicates.

vector<int> ivec;
 
.....  add all the entries you like ......
 
sort( ivec.begin(), ivec.end());
unique( ivec.begin), ivec.end());
 

I'm not going to say this is efficient because removing entries in the middle of a vector can be expensive.

[sicarie]

This is where the builtin STL functions come in handy.

First you sort the array and then use unique to remove adjacent duplicates.

vector<int> ivec;
 
.....  add all the entries you like ......
 
sort( ivec.begin(), ivec.end());
unique( ivec.begin), ivec.end());
 

I'm not going to say this is efficient because removing entries in the middle of a vector can be expensive.

Psh, well, if you want to do it the easy way.

@RRick - you ever going to answer my PM? ;)

[RRick]

Ironically, I have never used these functions, but I have a very good book.

A lot of us get stuck at the container level of STL and rarely venture beyond the iterators and containers. I consider the STL algorithms/functions to be the next step in my STL coding.

[gpkaur]

There is no unique function available for vectors in STL.
It is for list

[hsn]

if you want to do what you want to do by using vectors it will take you a while to do it. also it will be slow way.
by using set you only enter the values to the set and it will have only unique values.
for example
if you entered 'a' 'b' 'a' 'c'
in the set it will be 'a' 'b' 'c'. without calling any functions.

GOOD LUCK

[RRick]

Gpkaur, there is an STL unique function, but it's found in the <algorithm> header file, not in each object. List is "special" because it does have its own unique function.

The concept of the algorithm functions is that they work for all containers. Separate containers add their own algorithms when a specific need (usually speed) is required.