c++ vector bad access

Hi I have the following c++ program:

#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>
#include <boost/foreach.hpp>
#include <stdexcept>
#include <boost/flyweight.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/filesystem.hpp>

namespace fs = boost::filesystem;

struct entry
{
int file;
std::vector<double> a;
};


void my_file(const std::string&file, std::vector<entry> &data, int i){
try{
    std::ifstream in(file.c_str());
    entry e;
    std::string line;
    e.file = i;
    while(getline(in,line)){
        try{
            data[i].a.push_back( boost::lexical_cast<double> (line));
        }catch(boost::bad_lexical_cast bad){
            //std::cerr << bad.what() << std::endl;
        }
    }
}catch(std::runtime_error err){
    std::cerr << err.what() << std::endl;
}

}

void write_file(const std::string &file,std::vector<entry> data,const char* t_path){
try{
    std::string new_file = t_path ;
    new_file = new_file + "/" + file;
    std::ofstream f(new_file.c_str());

    for(size_t i = 0 ;i < data[1].a.size();i++){
        std::cout << "i: " << i;
        for(size_t j = 1; j < data.size();j++){
            std::cout << "j: " << j << std::endl;
            f << data[j].a[i]<< "\t";
        }
        f << "\n";
    }

}catch(std::runtime_error err){
    std::cerr << err.what()<< std::endl;
}
}


int collect_peak(const char*argv,const char*out){
std::cout << "collecting peaks\n";
std::stringstream sstr(argv);
std::string _line;
int c = 0;
std::vector<std::string> files;

while (getline(sstr,_line)){
    std::cout << _line << std::endl;
    fs::path p(_line);
    std::string tmp = p.parent_path().string() +"/_peak_" +      p.filename().string();
    files.push_back(tmp);
    c++;
}

std::cout << "c: " << c << std::endl;
std::vector<entry> data;
for (int i=0 ; i < files.size() ;++i){
    std::cout << files[i] <<std::endl;
    my_file(files[i],data,i);
}
write_file("__peak.txt",data,out);
return 0;

}

Somehow it always gives me a bad access in the my_file method. The program should actually to the following:

1. read multiple files that contain a caption and ten doubles seperated by a newline

2. output everything into one file so it looks like this:

   1. file \t 2. file \t 3. file \t ...

   2. file \t 2. file \t 3. file \t ...

   3. file \t 2. file \t 3. file \t ...

   4. file \t 2. file \t 3. file \t ...

   5. file \t 2. file \t 3. file \t ...

This actually worked already, but i reused it now in a different program. Any ideas?

Thank you