Solved

Count frequency of words in a file

Posted on 2012-04-08
8
236 Views
Last Modified: 2012-06-22
Hi

I have a file input.txt such as

amy
mish
lol
amy
vl
amy
mish

Can you help me write a simple c++ program that prints out

amy 3
mish 2
lol 1
vl 1
0
Comment
Question by:Vlearns
  • 3
  • 3
  • 2
8 Comments
 

Author Comment

by:Vlearns
ID: 37822517
here is the starter code

  1 #include <fstream>
  2 #include <string>
  3 #include <iostream>
  4 #include <sstream>
  5 #include <map>
  6 #include <vector>
  7 using namespace std;
  8
  9 int main() {
 10
 11 ifstream file("log");
 12 string   line;
 13 vector<int> pages;
 14 map<string,vector<int> > map1;
 15
 16 while(getline(file, line))
 17 {
 18     stringstream   linestream(line);
 19     string         data;
 20     string         val1;
 21     int            val2;
 22
 23    linestream >> val1
 24
 25    
 28    cout << " i am val1 " << val1 << endl;
 29
 30 }
 31 }
0
 
LVL 86

Expert Comment

by:jkr
ID: 37823868
A map is already a good approach, yet using a vector<int> as a value to that seems odd to me - you coud just

  map<string,int> wordmap;

  string word;
  // read word

  // ...

  map<string,int>::iterator i = wordmap.find(word);

  // has already an entry?
  if (wordmap.end() != i) {

    // yes, so increase count
    i->second++;

  }  else {

    // new word, insert it
    wordmap.insert(map<string,int>::value_type(word,1)); // initial integer value is '1'
  }

Open in new window

0
 

Author Comment

by:Vlearns
ID: 37824485
i think we need a vector to sort the words by their count, right? Your example does not print


amy 3
mish 2
lol 1
vl 1

sorted by their count, since maps cannt be sorted

 1 #include <fstream>
  2 #include <string>
  3 #include <iostream>
  4 #include <sstream>
  5 #include <map>
  6 #include <vector>
  7 using namespace std;
  8
  9 struct data{
 10     string word;
 11     int number;
 12 };  
 13
 14 int main() {
 15
 16 ifstream file("log");
 17 string   line;
 18 data dat1;
 19 vector<data> datavec;
 20
 21 while(getline(file, line))
 22 {  
 23    stringstream   linestream(line);
 24    string val1;
 25    
 26    linestream >> val1;
 27    
 28    iterate through the vector and find the if struct with string val exists, if yes increment the count of the structure,

else add a new element (struct) to the vector?
0
 
LVL 86

Expert Comment

by:jkr
ID: 37824569
Wel, I didn't think the printing part was necessary, but that woud be

  map<string,int> wordmap;

  string word;
  // read word

  // ...

  map<string,int>::iterator i = wordmap.find(word);

  // has already an entry?
  if (wordmap.end() != i) {

    // yes, so increase count
    i->second++;

  }  else {

    // new word, insert it
    wordmap.insert(map<string,int>::value_type(word,1)); // initial integer value is '1'
  }

// print resuts:

map<string,int>::const_iterator ci = wordmap.begin();

for (; ci != wordmap.end(); ++ci) {

  cout << ci->first << " " << ci->second << endl;
}
                                            

Open in new window

0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 

Author Comment

by:Vlearns
ID: 37824592
Hi jhr,

i do not think your solution will print/sort the strings by their counts
can you help me modify my vector of  structs based solution?

thanks!
0
 
LVL 86

Assisted Solution

by:jkr
jkr earned 300 total points
ID: 37824713
We, you are right, they are not sorted by their cont at the moment, but that can easiy be done:

  map<string,int> wordmap;

  string word;
  // read word

  // ...

  map<string,int>::iterator i = wordmap.find(word);

  // has already an entry?
  if (wordmap.end() != i) {

    // yes, so increase count
    i->second++;

  }  else {

    // new word, insert it
    wordmap.insert(map<string,int>::value_type(word,1)); // initial integer value is '1'
  }

// print results:
multimap<int,string> out; // using the count as a key wil cause the output 
                                          // to be sorted by that value

map<string,int>::const_iterator ci = wordmap.begin();

for (; ci != wordmap.end(); ++ci) {

  out.insert(multimap<int,string>::value_type(ci->second,ci->first));
}

multimap<int,string>::const_iterator ci2 = out.begin();                                 
  
for (; ci2 != out.end(); ++ci2) {

  cout << ci2->second << " " << ci->first << endl;
}
                                          

Open in new window

0
 
LVL 33

Expert Comment

by:sarabande
ID: 37827111
you don't need a find for counting. simply do

mymap[val1]++;

Open in new window


that statement would set count to 1 in case val1 was a new key or would increment the current count for val1 else.

to sort the results you could use std::map<int, std::vector<std::string> > mysortmap.

mysortmap[iter->second]->push_back(iter->first);

Open in new window


where iter would be iterator of the first map.

finally reverse iteration of mysortmap and inner loop which iterates element vector rev_iter->second would do what you needed.

Sara
0
 
LVL 33

Accepted Solution

by:
sarabande earned 200 total points
ID: 37827114
correction:

mysortmap[iter->second].push_back(iter->first);
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

IntroductionThis article is the second in a three part article series on the Visual Studio 2008 Debugger.  It provides tips in setting and using breakpoints. If not familiar with this debugger, you can find a basic introduction in the EE article loc…
Many modern programming languages support the concept of a property -- a class member that combines characteristics of both a data member and a method.  These are sometimes called "smart fields" because you can add logic that is applied automaticall…
The goal of the video will be to teach the user the concept of local variables and scope. An example of a locally defined variable will be given as well as an explanation of what scope is in C++. The local variable and concept of scope will be relat…
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

914 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now