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Assign multiple columns using := in data.table, by group
... hi hello 3.5 7 14 21
# 3: 3 3 hi hello 4.5 9 18 27
# 4: 1 4 hi hello 2.5 5 10 15
# 5: 2 5 hi hello 3.5 7 14 21
# 6: 3 6 hi hello 4.5 9 18 27
x[ , get("mynames") := list(mean(b) * 4, sum(b) * 3), by = a][] # same
# a b col1 co...
What is Android keystore file, and what is it used for?
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Gaurav Agarwal
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answered Jul 27 '11 at 19:13
OtraOtra
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Is MD5 still good enough to uniquely identify files?
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edited Oct 27 '10 at 10:40
answered Oct 27 '10 at 10:33
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How can I know which parts in the code are never used?
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answered Jan 27 '11 at 9:25
Matthieu M.Matthieu M.
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answered Feb 27 '13 at 3:47
BradBrad
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Is < faster than
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edited Aug 27 '12 at 20:28
answered Aug 27 '12 at 2:13
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How can I map True/False to 1/0 in a Pandas DataFrame?
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edited Apr 27 at 21:17
AMC
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answered Mar 27 '12 at 10:09
PranavPranav
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How to use php serialize() and unserialize()
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answered Dec 27 '11 at 6:54
deceze♦deceze
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answered Mar 27 '12 at 9:02
Simon NickersonSimon Nickerson
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