R language file-related operations

1. File System Introduction

The R language operates on file systems, including file operations and directory operations, and function APIs are defined in the base package.

2. Directory Operations

2.1 View Catalog

View subdirectories under the current directory.

Rgetwd()list.dirs()[1] "."     "./tmp"

View subdirectories and files for the current directory.

>dir ()[1] "readme.txt" "tmp" # View subdirectories and files for the specified directory. >dir (path= "/home/conan/r")[1] "A.txt" "Catools" [3] "Chinaweather" "Demorjava" [5] "env" "Fastrweb" [7] "Font" "FS" [9] "GitHub" "Linep ROF "[One]" Pryr "" Readme.txt "[[]" Rmysql "" Rserve "[[]" Rstudio-se Rver-0.97.551-amd64.deb "" WebSockets "[+]" x86_64-pc-linux-gnu-library "# lists only subdirectories or files that start with the letter R >dir (path= "/home/conan/r", pattern= ' ^r ')[1] "Rmysql" "Rserve" # Lists all directories and files in the directory, including hidden files, such as. A.txt>dir (path= "/home/conan/r", All.files=true)[1] "." ".." [3] ".                         A.txt "" A.txt "[5]" Catools "" Chinaweather "[7]" Demorjava " "ENV" [9] "fastrweb" "Font" [One] "FS" "GitHub" [13] "                            Lineprof "" Pryr "[[]]" readme.txt "" Rmysql "[+]" Rserve " "Rstudio-server-0.97.551-amd64.deb" [+] "websockets" "X86_64-pc-linux-gnu-library"

View subdirectories and files of the current directory, with the Dir () function.

list.files()list.files(".",all.files=TRUE)[1] "."          ".."         "readme.txt" "tmp"

View the complete catalog information.

file.info(".")  size isdir mode               mtime               ctime               atime  uid  gid uname grname. 4096  TRUE  775 2013-11-14 08:40:46 2013-11-14 08:40:46 2013-11-14 08:41:57 1000 1000 conan  file.info("./tmp")      size isdir mode               mtime               ctime               atime  uid  gid uname grname./tmp 4096  TRUE  775 2013-11-14 14:35:56 2013-11-14 14:35:56 2013-11-14 14:35:56 1000 1000 conan  conan

2.2 Creating a Directory

dir.create("create")list.dirs()[1] "."        "./create" "./tmp"

Create a 3 level subdirectory./a1/b2/c3

dir.create(path="a1/b2/c3")Warning message:In dir.create(path = "a1/b2/c3") :  dir.create(path="a1/b2/c3",recursive = TRUE)list.dirs()[1] "."          "./a1"       "./a1/b2"    "./a1/b2/c3" "./create"  system("tree").├── a1│   └── b2│       └── c3├── create├── readme.txt└── tmp

2.3 Checking if a directory exists

file.exists(".")file.exists("./a1/b2")file.exists("./aa")[1] FALSE

2.4 Checking the permissions of a directory

Check permissions for a directory

df<-dir(full.names = TRUE)file.access(df, 0) == 0./a1     ./create ./readme.txt        ./tmpTRUE         TRUE         TRUE         file.access(df, 1) == 0./a1     ./create ./readme.txt        ./tmpTRUE         TRUE        FALSE         file.access(df, 2) == 0./a1     ./create ./readme.txt        ./tmpTRUE         TRUE         TRUE         file.access(df, 4) == 0./a1     ./create ./readme.txt        ./tmpTRUE         TRUE         TRUE         TRUE

Modify directory permissions.

Sys.chmod("./create", mode = "0555", use_umask = TRUE) file.info("./create")         size isdir mode               mtime               ctime               atime  uid  gid uname grname./create 4096  TRUE  555 2013-11-14 08:36:28 2013-11-14 09:07:05 2013-11-14 08:36:39 1000 1000 conan  file.access(df, 2) == 0./a1     ./create ./readme.txt        ./tmpTRUE        FALSE         TRUE         TRUE

2.5 Duplicate names of directories

# 对tmp目录重命名> file.rename("tmp", "tmp2")dir()[1] "a1"         "create"     "readme.txt" "tmp2"

2.6 Deleting a directory

unlink("tmp2", recursive = TRUE)dir()[1] "a1"         "create"     "readme.txt"

2.7 Other function functions

Stitching directory Strings

file.path("p1","p2","p3")dir(file.path("a1","b2"))[1] "c3"

Get the bottommost subdirectory name

# 当前目录> getwd()[1] "/home/conan/R/fs"# 最底层子目录> dirname("/home/conan/R/fs/readme.txt")[1] "/home/conan/R/fs"# 最底层子目录或文件名> basename(getwd())[1] "fs">  basename("/home/conan/R/fs/readme.txt")[1] "readme.txt"

Convert file extension path

# 转换~为用户目录> path.expand("~/foo")[1] "/home/conan/foo"

Normalized path, used to convert the path delimiter of Win or Linux

# linux> normalizePath(c(R.home(), tempdir()))[1] "/usr/lib/R"      "/tmp/RtmpqNyjPD"# win> normalizePath(c(R.home(), tempdir()))[1] "C:\\Program Files\\R\\R-3.0.1"[2] "C:\\Users\\Administrator\\AppData\\Local\\Temp\\RtmpMtSnci"

Short path, reduce the display length of the path, only run in win.

# win> shortPathName(c(R.home(), tempdir()))[1] "C:\\PROGRA~1\\R\\R-30~1.1"[2] "C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\RTMPMT~1"

3. File operation

3.1 Viewing files

> dir()[1]  "create"  "readme.txt"# 检查文件是否存在> file.exists("readme.txt")[1] TRUE# 文件不存在> file.exists("readme.txt222")[1] FALSE# 查看文件完整信息> file.info("readme.txt")           size isdir mode               mtime               ctime               atime  uid  gid uname grnamereadme.txt    7 FALSE  664 2013-11-14 08:24:50 2013-11-14 08:24:50 2013-11-14 08:24:50 1000 1000 conan  conan# 查看文件访问权限，存在>  file.access("readme.txt",0)readme.txt         0# 不可执行>  file.access("readme.txt",1)readme.txt        -1# 可写>  file.access("readme.txt",2)readme.txt         0# 可读>  file.access("readme.txt",4)readme.txt         0# 查看一个不存在的文件访问权限，不存在> file.access("readme.txt222")readme.txt222           -1

Determine whether it is a file or a directory.

# 判断是否是目录> file_test("-d", "readme.txt")[1] FALSE> file_test("-d", "create")[1] TRUE# 判断是否是文件> file_test("-f", "readme.txt")[1] TRUE> file_test("-f", "create")[1] FALSE

3.2 Creating a file

# 创建一个空文件 A.txt> file.create("A.txt")[1] TRUE# 创建一个有内容的文件 B.txt> cat("file B\n", file = "B.txt")> dir()[1] "A.txt"      "B.txt"      "create"     "readme.txt"# 打印A.txt> readLines("A.txt")character(0)# 打印B.txt> readLines("B.txt")[1] "file B"

Merge the contents of the file B.txt into the A.txt.

# 合并文件> file.append("A.txt", rep("B.txt", 10)) [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE# 查看文件内容> readLines("A.txt") [1] "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B"

Copy the file A.txt to the file C.txt

# 复制文件> file.copy("A.txt", "C.txt")[1] TRUE# 查看文件内容> readLines("C.txt") [1] "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B" "file B"

3.3 Modifying file permissions

# 修改文件权限，创建者可读可写可执行，其他人无权限> Sys.chmod("A.txt", mode = "0700", use_umask = TRUE)# 查看文件信息> file.info("A.txt")      size isdir mode               mtime               ctime               atime  uid  gid uname grnameA.txt   70 FALSE  700 2013-11-14 12:55:18 2013-11-14 12:57:39 2013-11-14 12:55:26 1000 1000 conan  conan

3.4 File renaming

# 给文件A.txt重命名为AA.txt> file.rename("A.txt","AA.txt")[1] TRUE> dir()[1] "AA.txt"     "B.txt"      "create"     "C.txt"      "readme.txt"

3.5 Hard connections and soft connections

• A hard connection, which refers to a connection through an index node. In a Linux file system, a file saved in a disk partition, regardless of the type, assigns a number to it, called the index node number (Inode index). In Linux, multiple file names point to the same index node that exists. In general, this connection is a hard connection. The purpose of a hard connection is to allow a file to have multiple valid pathname, so that users can establish a hard connection to important files to prevent "accidental deletion" of the function. The reason for this is as above, because there is more than one connection to the index node that should be the directory. Deleting only one connection does not affect the index node itself and other connections, and the connection to the file's data block and directory will be released only if the last connection is deleted. That is, the condition that the file is actually deleted is that all the hard connection files associated with it are deleted.
• A soft connection, also called a symbolic connection (symbolic link). A soft-link file has a shortcut similar to Windows. It's actually a special file. In a symbolic connection, a file is actually a text file that contains location information for another file.

Hard and soft connections, only used in Linux systems.

# 硬连接> file.link("readme.txt", "hard_link.txt")[1] TRUE# 软连接> file.symlink("readme.txt", "soft_link.txt")[1] TRUE# 查看文件目录> system("ls -l")-rwx------ 1 conan conan   70 Nov 14 12:55 AA.txt-rw-rw-r-- 1 conan conan    7 Nov 14 12:51 B.txtdr-xr-xr-x 2 conan conan 4096 Nov 14 08:36 create-rw-rw-r-- 1 conan conan   70 Nov 14 12:56 C.txt-rw-rw-r-- 2 conan conan    7 Nov 14 08:24 hard_link.txt-rw-rw-r-- 2 conan conan    7 Nov 14 08:24 readme.txtlrwxrwxrwx 1 conan conan   10 Nov 14 13:11 soft_link.txt -> readme.txt

File Hard_link.txt is a file readme.txt hard connect file, file Soft_link.txt is a file Readme.txt soft connection file,

3.5 Deleting files

There are two functions that can use File.remove and unlink, where the unlink function is the same as the delete directory operation.

# 删除文件> file.remove("A.txt", "B.txt", "C.txt")[1] FALSE  TRUE  TRUE# 删除文件> unlink("readme.txt")# 查看目录文件> system("ls -l")total 12-rwx------ 1 conan conan   70 Nov 14 12:55 AA.txtdr-xr-xr-x 2 conan conan 4096 Nov 14 08:36 create-rw-rw-r-- 1 conan conan    7 Nov 14 08:24 hard_link.txtlrwxrwxrwx 1 conan conan   10 Nov 14 13:11 soft_link.txt -> readme.txt# 打印硬连接文件> readLines("hard_link.txt")[1] "file A"# 打印软连接文件，soft_link.txt，由于原文件被删除，有错误> readLines("soft_link.txt")Error in file(con, "r") : cannot open the connectionIn addition: Warning message:In file(con, "r") :  cannot open file ‘soft_link.txt‘: No such file or directory

4. A few special directories

• R.home () See the relevant directories for R software
• . Library View the contents of the R core package
• . Library.site View the directory of the R core package and the root user installation package directory
• . Libpaths () View the storage directory for all packages in R
• System.file () View the directory where the specified package resides

4.1 r.home () see the relevant directories for R software

# 打印R软件安装目录> R.home()[1] "/usr/lib/R"# 打印R软件bin的目录> R.home(component="bin")[1] "/usr/lib/R/bin"# 打印R软件文件的目录>  R.home(component="doc")[1] "/usr/share/R/doc"

The location of the R file is found through the system command.

# 检查系统中R文件的位置~ whereis RR: /usr/bin/R /etc/R /usr/lib/R /usr/bin/X11/R /usr/local/lib/R /usr/share/R /usr/share/man/man1/R.1.gz# 打印环境变量R_HOME~ echo $R_HOME/usr/lib/R

With the R.home () function, we can easily locate the directory of R software.

4.2 Package directory for R software

# 打印核心包的目录> .Library[1] "/usr/lib/R/library"# 打印核心包的目录和root用户安装包目录> .Library.site[1] "/usr/local/lib/R/site-library" "/usr/lib/R/site-library"[3] "/usr/lib/R/library"# 打印所有包的存放目录> .libPaths()[1] "/home/conan/R/x86_64-pc-linux-gnu-library/3.0"[2] "/usr/local/lib/R/site-library"[3] "/usr/lib/R/site-library"[4] "/usr/lib/R/library"

4.3 Viewing the directory where the specified package resides

# base包的存放目录> system.file()[1] "/usr/lib/R/library/base"# pryr包的存放目录>  system.file(package = "pryr")[1] "/home/conan/R/x86_64-pc-linux-gnu-library/3.0/pryr"

REF:

http://blog.fens.me/r-file-folder/

R language file-related operations