?
Solved

reading data file into a gsl matrix

Posted on 2006-07-20
3
Medium Priority
?
713 Views
Last Modified: 2008-03-10
Hi

both gsl_matrix_fread and gsl_matrix_fscanf require that matrix  must
be preallocated with the correct dimensions. now if I want to load the
data from a file and I don't know the number of rows and columns. do I
write a code to getline(in, line) and count++ or there is a better
way.
I know how to count the number of line from ifstream, but don't know howto get the number of words in one line which is the number of the column in the file, so that I can feed these info to the gsl_matrix for the size of the matrix to be allocated.

   ifstream in(file_name.c_str());
   string line = getline(in, line);
   stringstream input( line.c_str() ); <<-- error here
   
   string word;
   nCol = 0;
   while(inpput >> word)
      nCol++;

   nRows = 1;
   while (getline(in, line))
      nRows++;


thanks


0
Comment
Question by:samj
  • 3
3 Comments
 
LVL 12

Expert Comment

by:rajeev_devin
ID: 17152261
>> string line = getline(in, line);
This is a wrong syntax. It would be

string line;
getline(in, line);
0
 
LVL 12

Accepted Solution

by:
rajeev_devin earned 375 total points
ID: 17152273
Your modified code will be

ifstream in("data.txt");
string line;
getline(in, line);
stringstream input( line.c_str() );
      
string word;
int nCol = 0;
while(input >> word)
      nCol++;

int nRows = 1;
while (getline(in, line))
      nRows++;
0
 
LVL 12

Expert Comment

by:rajeev_devin
ID: 17152298
>> ifstream in("data.txt");
Change this to your previous statement.

ifstream in(file_name.c_str());
0

Featured Post

New feature and membership benefit!

New feature! Upgrade and increase expert visibility of your issues with Priority Questions.

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…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.

864 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