Re: [程式] R中的if條件

[memphis (讓你喜歡這世界~)]

try this

###
rm(list=ls())

v <- matrix(rnorm(176000*20), 176000, 20)
v[,1] <- sample(1:10, 176000, TRUE)

a <- 3

t.start <- Sys.time()
s1 <- which(v[,1] == a)
s2 <- which(v[,1] != a)
v[s1,1] <- v[s1,1] - a
v[s2,1] <- 12 - a + v[s2,1]
t.end <- Sys.time()

t.end - t.start

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→ piq:感謝建議^^