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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...
Repeat command automatically in Linux
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edited Nov 27 '12 at 22:05
answered Nov 27 '12 at 21:51
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OtraOtra
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How to check if a string contains only digits in Java [duplicate]
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BradBrad
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Is < faster than
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edited Aug 27 '12 at 20:28
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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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How to use php serialize() and unserialize()
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