NA value in RAPIDMINER?

Question

what is equivalent's of R ('NA'|'NULL'|'None') value in RAPIDMINER? Or what is some other value for denoting that this value should not be taken into consideration while making calculations, or that it is missing?

Answer 1

Missing values show up as '?' in the data view of example sets and they are counted in the meta-data view. Imported data can obviously have them and you can generate your own using the Declare Missing Values operator or within the Generate Attributes operator using a code fragment containing an invalid mathematical operation like 0/0. You can test for the presence of a missing value by using the missing() function within the Generate Attributes operator.

Answer 2

It is probabbly the question mark: ?