如何在R循环中修改i？

I have several large R objects saved as .RData files: "this.RData", "that.RData", "andTheOther.RData" and so on. I don't have enough memory, so I want to load each in a loop, extract some rows, and unload it. However, once I load(i), I need to strip the ".RData" part of (i) before I can do anything with objects "this", "that", "andTheOther". I want to do the opposite of what is described in How to iterate over file names in a R script? How can I do that? Thx

我有几个大的R对象保存为.RData文件:“this.RData”,“that.RData”,“andTheOther.RData”等等。我没有足够的内存,所以我想在循环中加载每个内容,提取一些行并卸载它。然而,一旦我加载(i),我需要剥离(i)的“.RData”部分,然后才能对“this”,“that”,“andTheOther”这些对象做任何事情。我想做的是如何在R脚本中迭代文件名中描述的内容?我怎样才能做到这一点?谢谢

Edit: I omitted to mention the files are not in the working directory and have a filepath as well. I came across Getting filename without extension in R and file_path_sans_ext takes out the extension but the rest of the path is still there.

编辑:我省略提到文件不在工作目录中并且也有文件路径。我在R中遇到了没有扩展名的获取文件名,而file_path_sans_ext取出了扩展名,但路径的其余部分仍然存在。

2 个解决方案

#1

Do you mean something like this?

你的意思是这样的吗?

i <- c("/path/to/this.RDat", "/another/path/to/that.RDat")
f <- gsub(".*/([^/]+)", "\\1", i)
f1 <- gsub("\\.RDat", "", f)
f1
[1] "this" "that"

On windows' paths you have to use "\\" instead of "/"

在Windows的路径上,您必须使用“\\”而不是“/”

Edit: Explanation. Technically, these are called "regular expressions" (regexps), not "patterns".

编辑:说明。从技术上讲,这些被称为“正则表达式”(regexps),而不是“模式”。

. any character

。任何角色
.* arbitrary number (including 0) of any kind of characters

。*任意类型的任意数字(包括0)
.*/ arbitrary number of any kind of characters, followed by a /

。* /任意类型的任意数字,后跟一个/
[^/] any character but not /

[^ /]任何角色但不是/
[^/]+ arbitrary number (1 or more) of any kind of characters, but not /

[^ /] +任意类型的任意数字(1或更多),但不是/
( and ) enclose groups. You can use the groups when replacing as \\1, \\2 etc.

(和)包围组。替换时可以使用组作为\\ 1,\\ 2等。

So, look for any kind of character, followed by /, followed by anything but not the path separator. Replace this with the "anything but not separator".

所以,寻找任何类型的字符,后跟/,后跟任何东西,但不是路径分隔符。将其替换为“除了分隔符之外的任何东西”。

There are many good tutorials for regexps, just look for it.

regexp有很多很好的教程,只需要寻找它。

#2

A simple way to do this using would be to extract the base name from the filepaths with base::basename() and then remove the file extension with tools::file_path_sans_ext().

使用base :: basename()从文件路径中提取基本名称然后使用tools :: file_path_sans_ext()删除文件扩展名的简单方法是使用base :: basename()从文件路径中提取基本名称。

paths_to_files <- c("./path/to/this.RData", "./another/path/to/that.RData")

tools::file_path_sans_ext(
  basename(
    paths_to_files
  )
)

## Returns:
## [1] "this" "that"

#1