Using gret l for Principles of Econometrics, 4th Edition

GNUPLOT

At the end of each chapter that follows you will find listings of the entire gretl script used to generate the results that are contained in it. When a graph is generated using gnuplotin a script or from the console, the output is written to a file that is placed in the working directory of gretl. If you are not sure where that is, click File>Working directory in the main gretl window to find or change this location. The location of the file will also be echoed to the screen so locating it should be fairly easy.

To view the graph and to edit it requires you to open the gnuplot program. In Windows, the easiest way to do this is to open the gretl console and type:

launch wgnuplot

This will look like

This opens gnuplot in a new window. Now, navigate to the gnuplot window and at the gnuplot command prompt type

load ’C:Tempgpttmp01.plt’

The path and filename inside the single quotes locates the file on your harddrive. Gretl places these plots into your working directory, which can be set using File>Working directory from the main gretl window. Figure 1.14 shows what this looks like.

Another way to do this is to open a command window (Figure 1.1) and type "C:Program Files (x86)gretlwgnuplot" at the command prompt. The double quotes are necessary since the folder name has a space in it. This will open the gnuplot program shown in Figure 1.14, from which you can search for and open graphs that are written to the harddrive. This implementation is a bit clumsy and is not very well documented in the gretl Users Guide at this point, but as with most things gretl it is a work in progress. By the time you read this, the situation could be much improved.

Although scripts are given to generate graphs in this text, the best way to do it is by using the GUI or from the console. Graphs generated via GUI or the console open to the screen. Once the graph is generated and visible on screen, a right-click of the mouse allows you to edit the graph and to save it in a variety of useful formats. That is what I have done in a number of graphs that follow to make them easier to read from the. pdf. Using gnuplot manually is really only necessary if your graphs are being generated in a script as some of the ones in this text are.

You do not have to accept gretl's default graph name. You can assign one yourself using the —output=filename, which sends your output to the specified filename.

Finally, there are a number of other types of plots you can do in gretl. These include boxplots, histograms, qqplots, and range/mean plots. The underlying engine that generates these is gnuplot, but gretl gives you easy access to their generation. You can also access gnuplot by script through File>Script files>New script>gnuplot script from the main menu.

Figure 1.14: The GNUPLOT program window. This is opened from within gretl by typing launch wgnuplot from the console. Type load ’filename’ to load ’filename’, which should include the correct path. In this case the file to load is ’C:Tempgpttmp01.plt’.