I'm very new to Java and I'm basically teaching myself. I'm writing a program where I need to plot some values. I have a while loop and I need to print x and y values to a text file that I can later graph using gnuplot. If someone can help me make two colums of x and y values to a text file I would really appreciate it!
gor.irina 0 Newbie Poster
NormR1 563 Posting Sage Team Colleague
By columns I assume you mean two fields of data separated by some spaces on the same line. The line ending with a newline character.
When you build the record insert the number of spaces between the two fields and add a newline char at the end:
String rec = dataForCol1 + " " + dataForCul2 + "\n";
If you want the second column to be line up vertically, then you need to compute the number of spaces to insert based on the length of the data in the first column.
jon.kiparsky 326 Posting Virtuoso
...or based on the second column if you want the columns to be right justified.
What sort of input does gnuplot want? Fixed-width, delimited?
gor.irina 0 Newbie Poster
It should look like the two columns of data on this website: http://sip.clarku.edu/tutorials/gnuplot/
NormR1 563 Posting Sage Team Colleague
Do you have any questions on how to create the file you need?
gor.irina 0 Newbie Poster
I do. I'm not sure what the right question to ask is, but when I tried writing
String rec = x + " " + y + "\n";
it didn't give me an output. I wrote that line in the middle of my while loop.
I also tried doing
System.out.printf("%1$10d%2$11.2f%3$10d%4$11.2f\n", x, y); earlier, and it gave me my x and y values alternating one after another in one list, not in two columns. I'm not sure what goes in the parenthesis before x, y for the printf command. Perhaps that might be my mistake?
NormR1 563 Posting Sage Team Colleague
Setting a String variable to a value does NOT create any output.
printf() will display the output on the console.
Your printf() args look too complicated for what you need.
System.out.printf("%f %f\n", x, y); gor.irina 0 Newbie Poster
How can I create an output?
NormR1 563 Posting Sage Team Colleague
What is an output?
gor.irina 0 Newbie Poster
Whoops! Sorry I didn't notice the rest of your message. The code works perfectly! Thank you so much. what does the %f and %f/n mean?
NormR1 563 Posting Sage Team Colleague
Read the API doc for the Formatter class. It is explained there.
java_programmer 0 Junior Poster
%f is formatter for float data type.
In Printf() function, you have to specify the formatter for data type - like %d for int, %s for String, %f for float etc. And /n implies new line. After printing each line, it will print a new line i.e. next output will be printed in a new line.
Whoops! Sorry I didn't notice the rest of your message. The code works perfectly! Thank you so much. what does the %f and %f/n mean?
java_programmer 0 Junior Poster
Mark the thread as solved, if your purpose solved.
%f is formatter for float data type.
In Printf() function, you have to specify the formatter for data type - like %d for int, %s for String, %f for float etc. And /n implies new line. After printing each line, it will print a new line i.e. next output will be printed in a new line.
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