r - How to use paste with for-loops?

Question

I am trying to use the function stri_join, from the library stringi in a loop, but I am having difficulties. I would like to obtain "A_1.png", "A_2.png", "A_3.png", "A_4.png", "A_5.png", and so on until "A_200.png".

Here is my attempt:

 x <- c(1:200)
 x
 for (i in 1:length(x)){
   Names <-paste("A_", 1:length(i), ".png",sep = "")
   print(Names)
 }

I obtain "A_1.png" 200 times. If you could point what I am missing.

Answer 1

我们不需要一个循环，因为它paste是矢量化的。所以要么使用sprintf

Names <- sprintf("A_%d.png", x)

或者paste

Names <- paste0("A_", x, ".png")

---

如果这是一个for循环练习，则初始化“Names”向量并将“Names”的每个元素分配给从paste

Names <- character(length(x))
for(i in seq_along(x)){
  Names[i] <- paste0("A_", i, ".png") 
}

Answer 2

stringi解决方案：

stri_paste("A_",1:200,".png")

使用从 1 到 200 的向量和“.png”粘贴“A_”。矢量化可以提供帮助，我们得到了预期的结果。