[gnuplot] How to create a data file for gnuplot?

I'm trying to make a graph with gnuplot. I specified my xrange, yrange, and labels, but when I typed in the following command:

gnuplot> plot "data.txt" using 1:2 with lines

gnuplot tells me:

warning: Skipping unreadable file "data.txt" No data in plot.

I don't understand how my data file is unreadable. This is what my data.txt looks like:

X       Y  [I didn't enter X and Y into my text file]

10000   0.030
5000    0.02
1000    0.012

I know I must be doing something wrong -- this is my first time using gnuplot. I tried doing a Google search on how to make a proper data.txt file turns up zilch.

EDIT:

I feel like this may sound strange to ask at a programming Q&A site, but what should a typical text file w/data look like? I'm no computer programmer, just an undergrad trying to plot a graph for her biochemistry class.

For future reference, I had the same problem

"warning: Skipping unreadable file"

under Linux. The reason was that I love using Tab-completing and in gnuplot this added a whitespace at the end that I did not really notice

gnuplot> plot "./datafile.txt "

I was having the exact same issue. The problem that I was having is that I hadn't saved the .plt file that I was typing into yet. The fix: I saved the .plt file in the same directory as the data that I was trying to plot and suddenly it worked! If they are in the same directory, you don't even need to specify a path, you can just put in the file name.

Below is exactly what was happening to me, and how I fixed it. The first line shows the problem we were both having. I saved in the second line, and the third line worked!

gnuplot> plot 'c:/Documents and Settings/User/Desktop/data.dat'
         warning: Skipping unreadable file c:/Documents and Settings/User/Desktop/data.dat
         No data in plot

gnuplot> save 'c:/Documents and Settings/User/Desktop/myfile.plt'

gnuplot> plot 'c:/Documents and Settings/User/Desktop/data.dat'

This error usually means the file couldn't be found.

Can you see the file from the command line?

1. Try specifying the full pathname.
2. check line ending type (use 0x0d).
3. is file open in another program?
4. do you have read access to it?

I had the same issue when tried to open the file using Plot->Data filename... option provided in the version for Windows 7 (by the way, it worked fine on another computer with the same version of the OP system).

Then I tried to change directory and save the .plt file, but it didn't work either. Finally, I tried to tape manually as it was showed for Linux earlier in this queue of posts:

gnuplot > plot "./datafile.dat"

and it worked!

Just go to the properties of your cmd.exe shortcut and change the 'start in' by adding the file name where you put all your '.txt' files.I had same problems and i put the whole file mane as 'D:\photon' in the 'start in' of the properties and it worked.Remember you have to put all your files in that folder otherwise you have to create many shortcuts for each data files.Sorry for late reply

Create your Datafile like this:

# X      Y
10000.0 0.01
100000.0 0.05
1000000.0 0.45

And plot it with

$ gnuplot -p -e "plot 'filename.dat'"

There is a good tutorial: http://www.gnuplotting.org/introduction/plotting-data/

Either as most people answered: the file doesn't exist / you're not specifying the path correctly.

Or, you're simply writing the syntax wrong (which you can't know unless you know what it should be like, right?, especially when in the "help" itself, it's wrong).

For gnuplot 4.6.0 on windows 7, terminal type set to windows

Make sure you specify the file's whole path to avoid looking for it where it's not (default seems to be "documents")

Make sure you use this syntax:

plot 'path\path\desireddatafile.txt'

NOT

plot "< path\path\desireddatafile.txt>"

NOR

plot "path\path\desireddatafile.txt"

also make sure your file is in the right format, like for .txt file format ANSI, not Unicode and such.