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DT <- data.table(
A = c("a", "a"),
B = c("b1", "b2"),
C = c("c1", "c2"),
D = c("d1", "d2"))
A B C D
1: a b1 c1 d1
2: a b2 c2 d2
Быстро и эффективно привести к виду:
A X b1 b2
1: a C c1 c2
2: a D d1 d2
Size: a a a
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> dcast(melt(DT, measure.vars = c("C", "D"), variable.name = "X"), A + X ~ B, value.var = "value")
A X b1 b2
1: a C c1 c2
2: a D d1 d2
АК
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> dcast(melt(DT, measure.vars = c("C", "D"), variable.name = "X"), A + X ~ B, value.var = "value")
A X b1 b2
1: a C c1 c2
2: a D d1 d2
ВL
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A
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pattern
функции list.files(). (Google)*(\.xlsx)*
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