Advanced Topics
Here you will find some explanations of advanced topics.
I hope this will help to understand how to use some more advanced things in LabPlot.

Topics

Errorbars
If you want to plot data with errorbars just import your data with the import dialog into a spreadsheet. Select the column X, Y and DX, DY that you want to use for errorbars. You than should select the corresponding plot (XYDY for Y errorbars, XYDXDY for X and Y errorbars and XYDYDY for 2 Y errorbars (up and down)).
If you use the data dialog to import your data directly into a plot select the correct type (x|y, x|y|dy, x|y|dx|dy or x|y|dy1|dy2) in the "read as" line edit.

TeX label
With version 1.5.0 LabPlot supports rendering of Tex label using texvc.
If you compile LabPlot yourself you only need a ocaml compiler present. When using a binary version of LabPlot texvc is automatically used when found in your $PATH.
For using TeX label you just have to activate the checkbox "TeX label" in the label dialog. With that every text you enter in the text box is rendered by texvc and plotted accordingly. Since this conversion takes some time you may see a certain delay when redrawing the plot.
Check out the "texlabel" example for getting a clue how it may look like.

Database import/export
LabPlot supports reading and writing data from a database using the KexiDB library. With KexiDB LabPlot can read and write data from PostgreSQL, mySQL, SQListe2+3. For importing data select "PostgreSQL, mySQL, etc." in the import dialog and browse through the database structure (tables and fields). For exporting data just select "DATABASE" in the export dialog and select the desired parameter.

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 Appearance 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 distant 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 '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-DDTHH: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.

Importing Origin OPJ files
Since many people are using the well known OriginLab Origin program LabPlot includes the feature to import Origin opj projects from versions ranging from 4.0 up to 7.5.
The OPJ file format is a proprietary file format so the import filter had to be developed by using reverse engineering techniques. This is the reason why it takes a lot of work to understand and convert Origin projects. Nonetheless with version 1.6.0 LabPLot supports all features of ORIGIN 7.5 projects using the latest version of liborigin.
If someone is willing to give some feedback and/or help i will continue to extend the features of this import filter.

XML project format
LabPlot 1.5.1 introduces a new project format based on XML. With some additions it should later comply with the OASIS standard.
The new XML format supports backward and forward compatibility and is much cleaner than the old LPL format. This format will be used in future releases as default project format and will replace the (old) LPL format Even though LabPlot will be able to read all old projects without any restriction.