在R中粘贴/折叠 [英] Paste/Collapse in R

问题描述

我对粘贴感到困惑，并认为这只是简单的串联。

I'm confused by paste, and thought it was just simple concatenating.

whales <- c("C","D","C","D","D")

quails <- c("D","D","D","D","D")

results <-paste(whales, quails, collapse = '')

为什么会返回 C DD DC DD DD D而不是CD DD CD DD DD？

Why would this return "C DD DC DD DD D" instead of CD DD CD DD DD?

此外，为什么会

results <-paste(whales[1], quails[1], collapse = '')

返回

CD吗？

有空格？

谢谢，
D

Thanks, D

EDIT

好的，我看到

results <-paste(whales, quails, collapse = NULL, sep='')

会得到我想要的信息，但是解释了为什么以前代码不起作用？还要感谢回答者。

will get me what I want, but an explanation of why the previous code didn't work? And also thank you to the answerers.

推荐答案

对于第一个问题，请尝试以下操作（与选择重复2个字符）。

For the first question, try the following (which might be more illustrative than choosing to repeat 2 characters).

### Note that R paste's together corresponding elements together...
paste(c("A", "S", "D", "F"), 
      c("W", "X", "Y", "Z"))

[1] "A W" "S X" "D Y" "F Z"

### Note that with collapse, R converts the above 
  # result into a length 1 character vector.
paste(c("A", "S", "D", "F"), 
      c("W", "X", "Y", "Z"), collapse = '')

[1] "A WS XD YF Z"

什么您真正想要做的（获得所需结果）如下：

What you really want to do (to get the "desired" result) is the following:

### "Desired" result:
paste(whales, quails, sep = '', collapse = ' ')

[1] "CD DD CD DD DD"

请注意，我们指定的是 sep 和崩溃不同值的参数，这与您的第二个问题有关。 sep 允许将每个术语用字符串分隔，而 collapse 允许将整个结果用字符分隔

Note that we are specifying the sep and collapse arguments to different values, which relates to your second question. sep allows each terms to be separated by a character string, whereas collapse allows the entire result to be separated by a character string.

尝试

paste(whales, quails, collapse = '', sep = '')

[1] "CDDDCDDDDD"

或者，使用快捷方式 paste0 ，该快捷方式默认为 paste ，其中 sep =''

Alternatively, use a shortcut paste0, which defaults to paste with sep = ''

paste0(whales, quails, collapse = '')

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