R控制结构双循环

Question

这是一段简单的代码:

for (i in c("red", "green"))
    for (j in c("blood", "trees")) {
        k <- paste(i, j, sep=" ")
        print(k)
    }
}

我希望它只输出"red blood"和"green trees".剩下的组合将被丢弃.这可以在循环中完成吗？

Answer 1

你不需要循环:

R> paste(c("red","green"), c("blood","trees"))

[1] "red blood"   "green trees"