La lettura di un file di Matrix txt e memorizzare in un array
https://stackoverflow.com/questions/572962
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Attualmente sto scrivendo un codice di ricottura simulata per risolvere un problema del commesso viaggiatore e hanno incontrato difficoltà con la conservazione e l'utilizzo i miei dati letti da un file txt. Ogni riga e colonna del file rappresenta ogni città, con la distanza tra due diverse città memorizzate come matrice 15 x 15:
0.0 5.0 5.0 6.0 7.0 2.0 5.0 2.0 1.0 5.0 5.0 1.0 2.0 7.1 5.0
5.0 0.0 5.0 5.0 5.0 2.0 5.0 1.0 5.0 6.0 6.0 6.0 6.0 1.0 7.1
5.0 5.0 0.0 6.0 1.0 6.0 5.0 5.0 1.0 6.0 5.0 7.0 1.0 5.0 6.0
6.0 5.0 6.0 0.0 5.0 2.0 1.0 6.0 5.0 6.0 2.0 1.0 2.0 1.0 5.0
7.0 5.0 1.0 5.0 0.0 7.0 1.0 1.0 2.0 1.0 5.0 6.0 2.0 2.0 5.0
2.0 2.0 6.0 2.0 7.0 0.0 5.0 5.0 6.0 5.0 2.0 5.0 1.0 2.0 5.0
5.0 5.0 5.0 1.0 1.0 5.0 0.0 2.0 6.0 1.0 5.0 7.0 5.0 1.0 6.0
2.0 1.0 5.0 6.0 1.0 5.0 2.0 0.0 7.0 6.0 2.0 1.0 1.0 5.0 2.0
1.0 5.0 1.0 5.0 2.0 6.0 6.0 7.0 0.0 5.0 5.0 5.0 1.0 6.0 6.0
5.0 6.0 6.0 6.0 1.0 5.0 1.0 6.0 5.0 0.0 7.0 1.0 2.0 5.0 2.0
5.0 6.0 5.0 2.0 5.0 2.0 5.0 2.0 5.0 7.0 0.0 2.0 1.0 2.0 1.0
1.0 6.0 7.0 1.0 6.0 5.0 7.0 1.0 5.0 1.0 2.0 0.0 5.0 6.0 5.0
2.0 6.0 1.0 2.0 2.0 1.0 5.0 1.0 1.0 2.0 1.0 5.0 0.0 7.0 6.0
7.0 1.0 5.0 1.0 2.0 2.0 1.0 5.0 6.0 5.0 2.0 6.0 7.0 0.0 5.0
5.0 7.0 6.0 5.0 5.0 5.0 6.0 2.0 6.0 2.0 1.0 5.0 6.0 5.0 0.0
Per leggere questo ho un LoadCities () funzionano come illustrato di seguito:
#include "iostream"
#include "fstream"
#include "string"
using namespace std;
double distances [15][15];
void LoadCities()
{
ifstream CityFile;
if (!CityFile.is_open()) //check is file has been opened
{
CityFile.open ("Cities.txt", ios::in | ios::out);
if (!CityFile)
{
cerr << "Failed to open " << CityFile << endl;
exit(EXIT_FAILURE); //abort program
}
}
int length;
char * buffer;
string cities;
CityFile.seekg(0, ios::end);
length = CityFile.tellg();
CityFile.seekg (0, ios::beg);
buffer = new char [length];
cities = CityFile.read (buffer,length);
string rows = strtok(cities, "\n");
distances = new double[rows.length()][rows.length()];
for (int i = 0; i < (string) rows.length(); i++)
{
string distance = strtok(rows[i], " ");
for (int j = 0; j < distance.length(); j++)
{
distances[i][j] = (double) Parse(distance[j]);
}
}
CityFile.close();
}
Ho tentato un metodo istreambuf_iterator alternativo per arrivare al punto di manipolare il materiale di lettura in array, però mi sembra sempre di incorrere in complicazioni:
ifstream CityFile("Cities.txt");
string theString((std::istreambuf_iterator<char>(CityFile)), std::istreambuf_iterator<char>());
Qualsiasi aiuto sarebbe molto appriciated. Stato colpire la testa contro questo con poco successo!
################ EDIT / Aggiornamento@ Soapbox - qualche dettaglio del codice SA, funzioni e main (). Questo non è pulito, efficiente, ordinata e non è mento per essere in questa fase, ha solo bisogno di lavorare per il momento. Questa versione (di seguito) funziona ed è impostato per risolvere i polinomi (problemi più semplici). Ciò che deve essere fatto per convertirlo in un problema del commesso viaggiatore è quello di:
-
Scrivi i LoadCities function () per raccogliere i dati a distanza. (Corrente)
-
Cambia Initialise () per ottenere il totale delle distanze
-
Cambia E () per la funzione TSP (ad esempio, calcolare la distanza di un percorso casuale)
Gli ultimi due So che posso fare, però ho bisogno LoadCities () per farlo. Niente altro ha bisogno di essere cambiato nel seguente script.
#include "math.h"
#include "iostream"
#include "fstream"
#include "time.h" // Define time()
#include "stdio.h" // Define printf()
#include "randomc.h" // Define classes for random number generators
#include "mersenne.cpp" // Include code for the chosen random number generator
using namespace std; // For the use of text generation in application
double T;
double T_initial;
double S;
double S_initial;
double S_current;
double S_trial;
double E_current;
int N_step; // Number of Iterations for State Search per Temperature
int N_max; //Number of Iterations for Temperature
int Write;
const double EXP = 2.718281828;
//------------------------------------------------------------------------------
//Problem Function of Primary Variable (Debugged 17/02/09 - Works as intended)
double E(double x) //ORIGNINAL
{
double y = x*x - 6*x + 2;
return y;
}
//------------------------------------------------------------------------------
//Random Number Generation Function (Mod 19/02/09 - Generated integers only & fixed sequence)
double Random_Number_Generator(double nHigh, double nLow)
{
int seed = (int)time(0); // Random seed
CRandomMersenne RanGen(seed); // Make instance of random number generator
double fr; // Random floating point number
fr = ((RanGen.Random() * (nHigh - nLow)) + nLow); // Generatres Random Interger between nLow & nHigh
return fr;
}
//------------------------------------------------------------------------------
//Initializing Function (Temp 17/02/09)
void Initialize() //E.g. Getting total Distance between Cities
{
S_initial = Random_Number_Generator(10, -10);
cout << "S_Initial: " << S_initial << endl;
}
//------------------------------------------------------------------------------
//Cooling Schedule Function (make variables) (Completed 16/02/09)
double Schedule(double Temp, int i) // Need to find cooling schedule
{
double CoolingRate = 0.9999;
return Temp *= CoolingRate;
}
//------------------------------------------------------------------------------
//Next State Function (Mod 18/02/09)
double Next_State(double T_current, int i)
{
S_trial = Random_Number_Generator(pow(3, 0.5), pow(3, 0.5)*-1);
S_trial += S_current;
double E_t = E(S_trial);
double E_c = E(S_current);
double deltaE = E_t - E_c; //Defines gradient of movement
if ( deltaE <= 0 ) //Downhill
{
S_current = S_trial;
E_current = E_t;
}
else //Uphill
{
double R = Random_Number_Generator(1,0); //pseudo random number generated
double Ratio = 1-(float)i/(float)N_max; //Control Parameter Convergence to 0
double ctrl_pram = pow(EXP, (-deltaE / T_current)); //Control Parameter
if (R < ctrl_pram*Ratio) //Checking
{
S_current = S_trial; //Expresses probability of uphill acceptance
E_current = E_t;
}
else
E_current = E_c;
}
return S_current;
}
//------------------------------------------------------------------------------
//Metropolis Function (Mod 18/02/09)
double Metropolis(double S_start, double T_current, int N_Steps, int N_temperatures)
{
S_current = S_start; //Initialised S_initial equated to S_current
for ( int i=1; i <= N_step; i++ ) //Iteration of neighbour states
S_current = Next_State(T_current, N_temperatures); //Determines acceptance of new states
return S_current;
}
//------------------------------------------------------------------------------
//Write Results to Notepad (Completed 18/02/09)
void WriteResults(double i, double T, double x, double y)
{
//This function opens a results file (if not already opened)
//and stores results for one time step
static ofstream OutputFile;
const int MAXLENGTH = 80;
if (!OutputFile.is_open()) //check is file has been opened
{
//no it hasn't. Get a file name and open it.
char FileName[MAXLENGTH];
//read file name
cout << "Enter file name: ";
do
{
cin.getline(FileName, MAXLENGTH);
}
while (strlen(FileName) <= 0); //try again if length of string is 0
//open file
OutputFile.open(FileName);
// check if file was opened successfully
if (!OutputFile)
{
cerr << "Failed to open " << FileName << endl;
exit(EXIT_FAILURE); //abort program
}
OutputFile << "Iterations" << '\t' << "Temperatures" << '\t' << "X-Value" << '\t' << "Y-Value" << endl;
OutputFile << endl;
}
//OutputFile.width(10);
OutputFile << i << '\t' << T << '\t' << x << '\t' << y << endl;
if (i == N_max)
{
OutputFile << endl
<< "Settings: " << endl
<< "Initial Temperature: " << T_initial << endl
<< "Temperature Iterations: " << N_max << endl
<< "Step Iterations: " << N_step << endl
<< endl
<< "Results: " << endl
<< "Final Temperature: " << T << endl
<< "Minimum: " << S << endl;
OutputFile.close();
}
}
//------------------------------------------------------------------------------
//Main SA Function (Mod 17/02/09)
void SA(int W)
{
S = S_initial;
T = T_initial;
for ( int N_temperatures = 1 ; N_temperatures <= N_max ; N_temperatures++ )
{
S = Metropolis( S, T, N_step, N_temperatures);
T = Schedule(T, N_temperatures);
if (W == 1)
WriteResults(N_temperatures, T, S, E_current);
}
cout << "Result" << endl
<< "Y-value> " << S << endl
<< "Temperature> " << T << endl;
}
//------------------------------------------------------------------------------
//Execution of Traveling Salesman Problem (Progress 18/02/09)
int main()
{
cout << "Quadratic Function" << endl
<< "Solving method: Simulated Annealing" << endl;
cout << "" << endl;
cout << "Select desired Initial Temperature:" << endl
<< "> ";
cin >> T_initial;
cout << "Select desired number of Temperature Iterations:" << endl
<< "> ";
cin >> N_max;
cout << "Select desired number of step Iterations:" << endl
<< "> ";
cin >> N_step;
Initialize();
cout << "Write to file: (1 / 0) " << endl
<< "> ";
cin >> Write;
SA(Write);
system ("PAUSE");
return 0;
}
@ Strager - So che il suo codice male, ma purtroppo con i vincoli di tempo coinvolti per il mio progetto e la curva di apprendimento consiquental, i risultati sono quelli che sono necessari! :) Sarà essere riordinato in ultime fasi.
@ dirkgently -. Questo è stato il motivo iniziale per farlo in questo modo, e, quindi, il motivo per cui il mio primo tentativo è quello di andare a esso in questo modo
Soluzione
Che ne dici di questo? ( BACIO soluzione)
void LoadCities() {
int x, y;
ifstream in("Cities.txt");
if (!in) {
cout << "Cannot open file.\n";
return;
}
for (y = 0; y < 15; y++) {
for (x = 0; x < 15; x++) {
in >> distances[x][y];
}
}
in.close();
}
funziona per me. Non potrebbe essere che complessa e forse non è molto performante, ma finché non si sta leggendo un array di 1000x1000, non si vedrà alcuna differenza.
Altri suggerimenti
Probabilmente si desidera qualcosa di più semplice, in questo modo:
std::vector<std::vector<std::string> > LoadCities(const std::string &filename)
{
using namespace std;
ifstream file;
file.open(filename, ios::in | ios::out);
if(!file.is_open()) {
// error
return vector<vector<double> >();
}
vector<vector<double> > data;
string line;
while(!std::getline(file, line, '\n').eof()) {
istringstream reader(line);
vector<double> lineData;
string::const_iterator i = line.begin();
while(!reader.eof()) {
double val;
reader << val;
if(reader.fail())
break;
lineData.push_back(val);
}
data.push_back(lineData);
}
return data;
}
In pratica si utilizza flussi di inserire i dati. Probabilmente sto facendo qualcosa di sbagliato (non ho mai affrontato iostreams; P)., Ma questo dovrebbe dare l'idea generale di come strutturare un lettore di matrice
Ha anche compilare? Ottengo ~ 7 errori. Un campione:
strtok(cities, "\n");
Il primo argomento di strtok() è un char * e non uno std :: string.
Fa questo aiuto?
void LoadCities()
{
std::vector<double> f((std::istream_iterator<double>
(std::ifstream("city.txt"))), /* replace filename with your own */
(std::istream_iterator<double>()));
if (!f.empty()) {
std::cout << f.size() << "\n";
/* print an arbitrary data point with 2 places of decimal */
std::cout << std::setprecision(2) << f[ 0 ] << std::endl;
}
}
Lavorare con le matrici non significa che è necessario disporre di un array multidimensionale. Soprattutto, con array 2D. Naturalmente è più facile da leggere e scrivere;)
Ecco come vorrei caricare / salvarlo:
#include <iostream>
#include <fstream>
#include <string>
int width = 0;
int height = 0;
double **distances;
void WriteDouble( std::ofstream &stream, double toWrite )
{
char buffer[8];
memcpy( buffer, &toWrite, 8 );
stream.write( buffer, 8 );
}
void WriteInt( std::ofstream &stream, int toWrite )
{
char buffer[4];
memcpy( buffer, &toWrite, 4 );
stream.write( buffer, 4 );
}
double ReadDouble( std::ifstream &stream )
{
double d = 0;
stream.read( (char *)&d, 8 );
return d;
}
int ReadInt( std::ifstream &stream )
{
int i = 0;
stream.read( (char *)&i, 4 );
return i;
}
void Save()
{
std::ofstream stream( "cities", std::ios::out | std::ios::binary );
if( !stream.good() ) {
throw std::exception( "Error opening stream" );
}
WriteInt( stream, width );
WriteInt( stream, height );
for( int x = 0; x < width; x++ ) {
for( int y = 0; y < height; y++ ) {
WriteDouble( stream, distances[x][y] );
}
}
stream.close();
}
void Load()
{
std::ifstream stream( "cities", std::ios::in | std::ios::binary );
if( !stream.good() ) {
throw std::exception( "Error opening stream" );
}
width = ReadInt( stream );
height = ReadInt( stream );
distances = new double *[width];
for( int i = 0; i < width; i++ ) {
distances[i] = new double[height];
}
for( int x = 0; x < width; x++ ) {
for( int y = 0; y < height; y++ ) {
distances[x][y] = ReadDouble( stream );
}
}
stream.close();
}
void RunSaveTest()
{
width = 15;
height = 15;
distances = new double *[width];
for( int i = 0; i < width; i++ ) {
distances[i] = new double[height];
}
for( int x = 0; x < width; x++ ) {
for( int y = 0; y < height; y++ ) {
distances[x][y] = (double)x / (double)( y + 1 );
std::cout << distances[x][y] << std::endl;
}
}
Save();
}
void RunLoadTest()
{
Load();
for( int x = 0; x < width; x++ ) {
for( int y = 0; y < height; y++ ) {
std::cout << distances[x][y] << std::endl;
}
}
}
int main()
{
RunSaveTest();
// RunLoadTest();
return 0;
}
Riferimento dal mio blog: http://www.topbug.net/blog/2013/01/10/load-a-matrix-from-an-ascii-format-file/
Questo frammento di codice ha una maggiore tolleranza ai guasti invece di assumere tutto è ben formattato.
#include <istream>
#include <string>
#include <sstream>
#include <vector>
// load matrix from an ascii text file.
void load_matrix(std::istream* is,
std::vector< std::vector<double> >* matrix,
const std::string& delim = " \t")
{
using namespace std;
string line;
string strnum;
// clear first
matrix->clear();
// parse line by line
while (getline(*is, line))
{
matrix->push_back(vector<double>());
for (string::const_iterator i = line.begin(); i != line.end(); ++ i)
{
// If i is not a delim, then append it to strnum
if (delim.find(*i) == string::npos)
{
strnum += *i;
if (i + 1 != line.end()) // If it's the last char, do not continue
continue;
}
// if strnum is still empty, it means the previous char is also a
// delim (several delims appear together). Ignore this char.
if (strnum.empty())
continue;
// If we reach here, we got a number. Convert it to double.
double number;
istringstream(strnum) >> number;
matrix->back().push_back(number);
strnum.clear();
}
}
}
// example
#include <fstream>
#include <iostream>
int main()
{
using namespace std;
// read the file
std::ifstream is("input.txt");
// load the matrix
std::vector< std::vector<double> > matrix;
load_matrix(&is, &matrix);
// print out the matrix
cout << "The matrix is:" << endl;
for (std::vector< std::vector<double> >::const_iterator it = matrix.begin(); it != matrix.end(); ++ it)
{
for (std::vector<double>::const_iterator itit = it->begin(); itit != it->end(); ++ itit)
cout << *itit << '\t';
cout << endl;
}
return 0;
}
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