R控制结构双回路

Question

下面是一个简单的代码：

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

我将它想只输出"red blood"和"green trees"。剩下的组合将被丢弃。这可以在循环内完成吗？

Answer 1

你并不需要一个循环：

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

[1] "red blood" "green trees"