How to read .txt file with x and y values and convert it into an array?

Question

I need to convert a .txt file into arrays and will then plot it in a graph. My problem is this:

I have a text file containing x,y values:

image here for x and y values

and so on.....(so many values)

and i want to convert it into arrays:

double [] x= { 23, 26, 45, 32, 43, 46,...}
double [] y= { 92, 16, 14, 11, 17, 58,...}

This arrays will be set in a graph, but i need to set this first into arrays for me to plot it.

I still don't have a code for this yet. Please help :(

This seems like an assignment question, asking such questions directly is discouraged. A better way would be to split your problems into smaller problems e.g. 1) how to read a txt file in a particular programming language e.g. ruby 2) how to use arrays in ruby, and then you should try to connect these dots to complete your assignment. Also these questions are trivial and you need to search existing question base before posting them as new questions. — Usman, Jun 12 '16 at 21:27

Ankit Deshpande · Answer 1 · 2016-06-08T19:51:44.530

1

public class ReadFile{
    public static void main(String[] args){
        BufferedReader br  = new BufferedReader(new BufferedReader(new FileReader("pathToFile")));
        String line = "";
        // reading when each line has x, y
        while((line = br.readLine())!=null){
             String[] t = line.split(",");
             double x = Double.parseDouble(t[0].trim());
             double y = Double.parseDouble(t[1].trim());
             // store it in the array/list
             // or create a Class Pair having x & y coordinate      
        } 
    }
}

with Pair class it will look like this

class Pair{
   double x , y;
   Pair(double x , double y){
     this.x = x;
     this.y = y;
   }
}

// the reading logic
    public class ReadFile{
        public static void main(String[] args){
            List<Pair> pointList = new ArrayList<Pair>();
            BufferedReader br  = new BufferedReader(new BufferedReader(new FileReader("pathToFile")));
            String line = "";
            while((line = br.readLine())!=null){
                 String[] t = line.split(",");
                 double x = Double.parseDouble(t[0].trim());
                 double y = Double.parseDouble(t[1].trim());
                 // store it in the array/list
                 // or create a Class Pair having x & y coordinate
                 Pair p = new Pair(x,y);
                 pointList.add(p);       
            } 
        }
    }

edited Jun 08 '16 at 19:51

answered Jun 08 '16 at 19:43

Ankit Deshpande

3,476
1
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No reason to create a class for pairs `java.awt.Point` or `java.awt.geom.Point2D.Double` should be fine – OneCricketeer Jun 08 '16 at 19:45
In the question he is converting them into a double array, to use `java.awt.Point` he'll need integer values – Ankit Deshpande Jun 08 '16 at 19:49
1

Sure, which is why I mentioned the second option – OneCricketeer Jun 08 '16 at 19:50
Thank you! Now, my only problem is to graph this arrays. I'm still looking for ways how to graph it. Again, thank you very much! – Johanna Jun 08 '16 at 21:17
take a look at this link http://stackoverflow.com/questions/1277126/plot-graphs-in-java – Ankit Deshpande Jun 09 '16 at 07:27
Thanks, but we're not allowed to use jfreechart... :( – Johanna Jun 09 '16 at 08:42

score 1 · Answer 2 · answered Jun 08 '16 at 19:46

Since you do not know upfront how many vertices you have, consider using two List collections in place of two arrays.

This would let you follow the algorithm below:

Prepare two lists, listx and listy
In a loop, read two integers, x and y
If two integers are not available, exit the loop
Otherwise, add x to listx and y to listy

Once the loop is over, you have your points in two parallel collections.

How to read .txt file with x and y values and convert it into an array?

2 Answers2