3.1.15: Select Element

All structural elements can be given identifiers, i.e. names. Names are case sensitive and need to start with a letter or underscore. After the first initial letter numbers and letters may follow. Names need not be unique: Two elements can have the same name without Karamba3D complaining. Each element has a default identifier: its index. This is the reason why it is not allowed to have an integer number as an element identifier. Fig. 3.1.15.1 shows how a list of elements can be split into two data trees using their identifiers. The “Select Beam”-component expects a list of elements in “Elems” as well as a list of identifiers or regular expressions in “Id”. Regular expressions need to be prefixed by a “&”. They represent a very mighty selection tool. In fig. 3.1.15.1 one can see three use-cases:

• “&.[1-2]”: a “.” matches any character; “[1-2]” matches one character in the range of “1” to “2”. This is equivalent to “[12]”.

• “&b.”: matches any identifier that starts with “b” followed by an arbitrary character.

• “&.[13]”: matches any identifier that starts with an arbitrary character followed either by “1” or “3”.

Fig. 3.1.15.1: Elements can be selected by using their identifiers

There are two output-plugs on the “Select Beam”-component: “SElem” renders the selected elements which match the selection criteria, “RElem” returns the rest. The entries of the “SElem” and “RElem” output data remember their spot in the original list of elements. Joining them results in the original order of elements.