GNUPLOT: extract binary 2D array and print

Question

I am struggling with GNUPLOT binary data handling.

I have a binary file, printed by MATLAB frite function, which prints in column order.

I am printing a Nx2 array, that is a collection of points on xy plane, that I guess is stored as x1..xn y1..yn, as consecutive records in the binary file. Do you agree? Consider that I still have a not clear idea of what binary storage means. I am used to ASCII files, with nice separators and \n's.

So I want to plot these points with gnuplot. I have been reading the binary general documentation and I ended trying this:

plot 'datafile.bin' binary array=N:N w l

that means that my data file is made by two arrays, each one of N elements. Gnuplot produces one line, first following the values of the first array, then following the values of the second array, both of them on the interval 1:N.

I tried to use the first array as x axis of my plot and the second array as y axis, So I try:

plot 'datafile.bin' binary array=N:N u 1:2 w l

It plots the two arrays again consecutively, not in a xy plot. Where am I wrong?

Many thanks

EDIT: I tried to apply the scan=xy keyword to both the lines, but he told me that my file is a unidimensional record. So I guess that u 1:2 has no sense

Answer 1

I don't think gnuplot can handle the data type you describe. It doesn't know about arrays and matrices like matlab does.

Write your data file with pairs of x,y values.

Then you can

 plot dataf binary format='%float%float' using 1:2". 

(if your x,y values are both floats).

The "array" keyword is meant for the case when your file only contains the function values and you want gnuplot to construct the independent variable(s). Totally different.