NoDataError

MDAnalysis defines the NoDataError exception for cases when there's insufficient data to operate on. This can happen, for instance, when a selection did not match anything.

Until release 0.7.5.1 a NoDataError was raised for selections that did not match anything or an AtomGroup built from an empty list (Issue 12) but this has been changed in release 0.7.6 to return simply an empty AtomGroup.