No subject
Fri Jan 14 16:09:15 CET 2011
o .SD no longer includes 'by' columns, FR#978. This resolves
the long standing annoyance of duplicated 'by' columns
when the j expression returns a subset of rows from .SD.
For example, the following query no longer contains
a redundant 'colA.1' duplicate.
DT[,.SD[2],by=colA] # 2nd row of each group
Any existing code that uses .SD may require simple
changes to remove workarounds. If columns have been
referenced by name, as recommended where possible, then
no changes to existing code should be required.
Matthew
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