Selection Expressions

The sel command defines a selection expression that allows you to save a data threshold, then re-issue the named selection expression later with the see command.

To demonstrate this command, let's start Partiview with the Sample Data set. If we issue the datavar command, we can see that we have a color, luminosity, and label variable. Let's threshold the data by color via the command

only= color 4

This displays the orange particles, of which there are about 1000. Now, let's save this setting to a selection expression called “orange” using the command

sel orange = thresh

Refine the displayed data by removing dimmer data using the command

only- lumin <80

and call this “brightorange” in the command

sel brightorange = thresh

Now, we can toggle between these modes using the see command. The see command takes one argument, the name of a selection expression. There are several pre-defined selection expressions: all, none, and thresh.

Let's return all the Sample Data to view using the command

see all

Now we can toggle our saved expressions in these commands

see orange

displaying only those particles with color = 4. Now, we can see only the bright particles using the other expression we defined earlier

see brightorange

If we have only one threshold for a data set, we can use see thresh to toggle between seeing all the data and only the threshed data.

Selection expressions are best defined in config or data files to pre-load different views of your data set.

Digital Universe Atlas

Partiview User's Guide

Selection Expressions

Selection Expressions