正则表达式的含义，如 - \\d、\\D、^、$ 等
Meaning of regular expressions like - \\d , \\D, ^ , $ etc
这些表达是什么意思？我在哪里可以了解它们的用法？
\d
\D
\s
\S
\w
\W
\t
\n
^
$
\
| etc..
我需要使用 stringr 包，但我完全不知道如何使用它们。
来自 ?regexp，在 扩展正则表达式 部分：
The caret ‘^’ and the dollar sign ‘$’ are metacharacters that
respectively match the empty string at the beginning and end of a
line. The symbols ‘\<’ and ‘>’ match the empty string at the
beginning and end of a word. The symbol ‘\b’ matches the empty
string at either edge of a word, and ‘\B’ matches the empty string
provided it is not at an edge of a word. (The interpretation of
‘word’ depends on the locale and implementation: these are all
extensions.)
来自类似 Perl 的正则表达式:
The escape sequences ‘\d’, ‘\s’ and ‘\w’ represent any decimal
digit, space character and ‘word’ character (letter, digit or
underscore in the current locale: in UTF-8 mode only ASCII letters
and digits are considered) respectively, and their upper-case
versions represent their negation. Vertical tab was not regarded
as a space character in a ‘C’ locale before PCRE 8.34 (included in
R 3.0.3). Sequences ‘\h’, ‘\v’, ‘\H’ and ‘\V’ match horizontal
and vertical space or the negation. (In UTF-8 mode, these do
match non-ASCII Unicode code points.)
请注意，在 R 输入中反斜杠通常需要 doubled/protected，例如您将使用 "\h" 来匹配水平 space.
来自 ?Quotes:
Backslash is used to start an escape sequence inside character
constants. Escaping a character not in the following table is an
error.
\n newline
\r carriage return
\t tab
正如其他人在上面评论的那样，如果您是第一次开始使用正则表达式，您可能需要更多帮助。这对于 Whosebug 来说有点题外话（指向站外资源的链接），但在 gsubfn package overview 的底部有一些指向正则表达式资源的链接。或者 Google "regular expression tutorial" ...
这些表达是什么意思？我在哪里可以了解它们的用法？
\d
\D
\s
\S
\w
\W
\t
\n
^
$
\
| etc..
我需要使用 stringr 包，但我完全不知道如何使用它们。
来自 ?regexp，在 扩展正则表达式 部分：
The caret ‘^’ and the dollar sign ‘$’ are metacharacters that respectively match the empty string at the beginning and end of a line. The symbols ‘\<’ and ‘>’ match the empty string at the beginning and end of a word. The symbol ‘\b’ matches the empty string at either edge of a word, and ‘\B’ matches the empty string provided it is not at an edge of a word. (The interpretation of ‘word’ depends on the locale and implementation: these are all extensions.)
来自类似 Perl 的正则表达式:
The escape sequences ‘\d’, ‘\s’ and ‘\w’ represent any decimal digit, space character and ‘word’ character (letter, digit or underscore in the current locale: in UTF-8 mode only ASCII letters and digits are considered) respectively, and their upper-case versions represent their negation. Vertical tab was not regarded as a space character in a ‘C’ locale before PCRE 8.34 (included in R 3.0.3). Sequences ‘\h’, ‘\v’, ‘\H’ and ‘\V’ match horizontal and vertical space or the negation. (In UTF-8 mode, these do match non-ASCII Unicode code points.)
请注意，在 R 输入中反斜杠通常需要 doubled/protected，例如您将使用 "\h" 来匹配水平 space.
来自 ?Quotes:
Backslash is used to start an escape sequence inside character constants. Escaping a character not in the following table is an error.
\n newline
\r carriage return
\t tab
正如其他人在上面评论的那样，如果您是第一次开始使用正则表达式，您可能需要更多帮助。这对于 Whosebug 来说有点题外话（指向站外资源的链接），但在 gsubfn package overview 的底部有一些指向正则表达式资源的链接。或者 Google "regular expression tutorial" ...