Chapter 6. Advanced Topics

Here you will find some explainations of advanced topics.

I hope this will help to understand how to use some more complicated things in LabPlot.

multiple plots

Since version 1.3.0 LabPlot supports multiple plots on a worksheet. New plots can easily be added to a worksheet by choosing "New 2D Plot", "New 3D Plot", etc. A new plot is opened automatically when opening a function or data dialog for a plot with different type than the active plot. SO if you have an active 2d plot and select "New 3D Function" a new 3d plot is automatically added.

With the "Arrange Plots" item in the Apperance Menu you can easily arrange the plots on a worksheet. The grid for arranging the plots can be selected with numbers (like 2x2) and the distants between the plots and between a plot and the worksheet border can be set with the gap.

You can also arrange plots on a worksheet by hand. With dragging the border of a plot you can scale a plot as needed. When moving the mouse over the borders of a plot, you will see the corresponding arrows.

A whole plot can be moved by drag and drop when clicking in the center of a plot. You will see a cross arrow when reaching the center of a plot.

using date and time formats

When reading data in the data dialog you can specify the format for reading a column not only to double (default) but also to time and date. LabPlot uses QT's fromString() function to convert a column to a valid date or time. So it really depends on that function what date and time formats are valid. It seems, when selecting "date", the format of the column needs to be YYYY-MM-DD.

In the axes dialog you can select 3 different formats for the tic label : date, time and datetime format. With "date" selected the values are evaluated as day since 1.1.1970. With "time" selected the values are evaluated as seconds. Finally with "datetime" the values are evaluated as seconds since 1.1.1970. You can specify the shown format of the tic label by specifying a certain string in the format line edit.

Since version 1.4.0 LabPlot can import data in datetime format too. Two different formats can be selected. The text format looks like the output of "date" (locale-specific changes should be no problem) and the ISO format in the format "YYYY-MM-DTHH:MM:SS".

QWT 3D Plots

Since version 1.4.0 LabPlot uses the nice library qwtplot3d to realize a more sophisticated 3 dimensional plot. For compatibility reasons the simple 3D plot is still existing and still has some advantages over the 3D plot of QWT. But i would recommend to use the QWT 3D plot when possible.

The QWT 3D plot uses OpenGL so you can easily rotate, scale and shift the plot with the mouse. In the plot settings dialog (appearance menu) you can define more settings of this 3 dimensional plot.

GRASS

LabPlot has (up to now) very limited support for GRASS plots. Of course you need GRASS installed to use this features in LabPlot. It uses GRASSQt to bind the GRASS functionality to QT.

Please let me know if you like to use more functions of GRASS directly in LabPlot.