[datatable-help] v1.5.3 has just been pushed to CRAN
Bacou, Melanie
mel at mbacou.com
Fri Feb 11 03:43:17 CET 2011
Matt,
This is fantastic! Eight more reasons to rely on data.table for my daily
research tasks. Thanks so much for your efforts.
--Mel.
-----Original Message-----
From: datatable-help-bounces at r-forge.wu-wien.ac.at
[mailto:datatable-help-bounces at r-forge.wu-wien.ac.at] On Behalf Of Matthew
Dowle
Sent: Thursday, February 10, 2011 8:00 PM
To: datatable-help at lists.r-forge.r-project.org
Subject: [datatable-help] v1.5.3 has just been pushed to CRAN
NEW FEATURES
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.
o 'by' may now be a character vector of column names.
This allows syntax such as DT[,sum(x),by=key(DT)].
o X[Y] now includes Y's non-join columns, as most users
naturally expect, FR#746. Please do use j in one step
(i.e. X[Y,j]) since that merges just the columns j uses and
is much more efficient than X[Y][,j] or merge(X,Y)[,j].
o The 'Join Inherited Scope' feature is back on, FR#1095. This
is consistent with X[Y] including Y's non-join columns, enabling
natural progression from X[Y] to X[Y,j]. j sees columns in X
first then Y.
If the same column name exists in both X and Y, the data in
Y can be accessed via a prefix "i." (not yet implemented).
o Ad hoc by now coerces double to integer (provided they are
all.equal) and character to factor, FR#1051, as setkey
already does.
USER-VISIBLE CHANGES
o The default for mult is now "all", as planned and
prior notice given in FAQ 2.2.
o ?[.data.table has been merged into ?data.table and updated,
simplified, corrected and formatted.
DEPRECATED & DEFUNCT
o The DT() alias is now fully deprecated, as warned
in NEWS for v1.4, and FAQs 2.6 and 2.7.
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