DataLab is a compact statistics package aimed at exploratory data analysis. Please visit the DataLab Web site for more information....

## Guided Tour: How to Mark Data

In many situations it is quite useful to mark part of the data for further special processing. For example you may want to identify outliers, or to change the class properties of some data, or you may want to limit data to a certain extent. All these tasks can be solved by marking the objects in question and performing some further actions on the marked data.

Basically, there are several ways to mark data: markings can be performed either graphically by using the "mark data" button in the diagram windows, or numerically by using the numeric data editor.

Let's do some practical work in order to show how to mark data graphically. Click the "mark data" button in the x-y-chart of our previous example. Now you can enter a rectangular area within the data window defining the area where data are to be marked. You therefore move the cursor to one corner of the intended area and click and hold down the left mouse button. Moving the mouse while holding down the button displays a rubber band rectangle which indicates the area to be marked. Note, that this marking process behaves like a toggle switch: by marking the same area again existing markings are removed. This feature can be used to create arbitrarily complex areas for markings. The marked data are indicated by crosses in the data plots.

You may also mark data within the numeric data editor. Therefore click the command Edit/Data/Numerical. This starts up the numeric data editor which primarily serves to enter data manually. Marked data are indicated by numbers displayed in different colors (red or blue, by default). You can mark individual ranges of data points by first selecting the corresponding matrix cells and then clicking one of the marking buttons (, ) at the top of the editor window. For a detailed description of further options please refer to the corresponding help page.

Now, that you have marked some data you can selectively perform some actions on these marked data. You can for example set the marked data to a constant value, or apply a formula to the marked data, or remove all marked objects from the data table, or assign new class information to these data.

Last Update: 2013-Feb-13