Question

我想输出这个：

This is the text [1] from process
This is the text [2] from process
This is the text [3] from process

如何使用for循环创建它？我尝试了什么：

for (i in 1:3) {
                  query_line<- "This is the text["+i+"]from process"
  }

错误是：

Error in "This is the text[" + i : non-numeric argument to binary operator

Answer 1

您可以使用?cat：

for (i in 1:3) {
    cat("This is the text [", i, "] from process\n")
}
#This is the text [ 1 ] from process
#This is the text [ 2 ] from process
#This is the text [ 3 ] from process

如果您只想将其存储在变量中，可以执行以下操作（不要忘记提前初始化存储变量）：

n <- 3
res <- character(n)
for (i in 1:n) {
   res[i] <- paste("This is the text [", i, "] from process")
}

然后，结果存储在res：

中

res
#[1] "This is the text [ 1 ] from process" "This is the text [ 2 ] from process"
#[3] "This is the text [ 3 ] from process"

但是，如果您真的只想创建一个包含该文本的字符向量，则可以在一次paste调用中执行此操作：

paste("This is the text [", 1:3, "] from process")
#[1] "This is the text [ 1 ] from process" "This is the text [ 2 ] from process"
#[3] "This is the text [ 3 ] from process"

Answer 2

您还可以使用生成诊断消息的message函数。它以红色显示。

 for (i in 1:5)
 message(paste("This is the text [",i,"] from process",sep=""))

在for循环中使用计数器来计算结果

2 个答案: