如何使用循环创建一个字符串的向量？ [英] How to create a vector of character strings using a loop?

问题描述

我试图使用循环在R中创建一个字符串的向量，但我有一些麻烦。我非常感谢任何人都能提供帮助。

I am trying to create a vector of character strings in R using a loop, but am having some trouble. I'd appreciate any help anyone can offer.

我使用的代码有点详细，但我已经尝试编写一个可重复的示例捕获所有关键位：

The code I'm working with is a bit more detailed, but I've tried to code a reproducible example here which captures all the key bits:

vector1<-c(1,2,3,4,5,6,7,8,9,10)
vector2<-c(1,2,3,4,5,6,7,8,9,10)
thing<-character(10)


for(i in 1:10) {
  line1<-vector1[i]
  line2<-vector2[i]
  thing[i]<-cat(line1,line2,sep="\n") 
}

如下：

1
1

Error in thing[i] <- cat(line1, line2, sep = "\n") : 
  replacement has length zero

我想实现的是一个字符向量，其中每个字符分成两行，使 thing [1] 是

What I'm trying to achieve is a character vector where each character is split over two lines, such that thing[1] is

1
1

和 thing [2] 是

2
2

等。有谁知道我怎么能这样做？

and so on. Does anyone know how I could do this?

推荐答案

cat 打印到屏幕， $ c> NULL - 要连接到一个新的字符向量，您需要使用粘贴：

cat prints to the screen, but it returns NULL- to concatenate to a new character vector, you need to use paste:

  thing[i]<-paste(line1,line2,sep="\n") 

例如在交互式终端中：

> line1 = "hello"
> line2 = "world"
> paste(line1,line2,sep="\n") 
[1] "hello\nworld"
> ret <- cat(line1,line2,sep="\n") 
hello
world
> ret
NULL

虽然注意到在你的情况下，整个for循环可以被替换具有更简洁和高效的行：

Though note that in your case, the entire for loop could just be replaced with the more concise and efficient line:

thing <- paste(vector1, vector2, sep="\n")
#  [1] "1\n1"   "2\n2"   "3\n3"   "4\n4"   "5\n5"   "6\n6"   "7\n7"   "8\n8"  
#  [9] "9\n9"   "10\n10"

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