带有可选小数和反向引用的 sed 数字 [英] sed digits with optional decimal and backreference

问题描述

我有这样的简单输入:

11111(n)
222222(p)
33333333(:)

我可以使用 sed 反向引用将括号与这样的数字交换:

I can use sed backreference to swap parenthesis with digits like this :

sed -e 's/\([[:digit:]]*\)\((.*)\)/\2 \1/' file

产生

(n) 11111
(p) 222222
(:) 33333333

很酷！

但是对于潜在的十进制数字，事情变得更加困难，就像这样

But things became more difficult with potential decimal digits, like this

11111(n)
11111.111(n)
2222222.22(p)
33.3333333(:)

我尝试了很多命令，比如

I've try many commands, like

sed -e 's/\([[:digit:]]*(\.[[:digit:]]*?)\)\((.*)\)/\2 \1/' file
sed -e 's/\([[:digit:]]*\.?[[:digit:]]*?)\)\((.*)\)/\2 \1/' file
sed -e 's/\([[:digit:]]*\.*[[:digit:]]*)\)\((.*)\)/\2 \1/' file
sed -e 's/\([[:digit:]]*.*[[:digit:]]*)\)\((.*)\)/\2 \1/' file

所需的输出:

(n) 11111
(n) 11111.111
(p) 2222222.22
(:) 33.3333333

注意数字可以是任意长(1到n位)，小数点(.)和十进制数字是可选的.

Note that digits can be arbitrary long (1 to n digits), and decimal mark (.) and decimal digits are optional.

此外，sed 似乎没有 \d 速记，正如 stackexchange

Furthermore, sed don't seem to have \d shorthand, as pointed in stackexchange

推荐答案

当您知道在 POSIX 括号表达式中使用 [:digit:] 匹配什么时，它变得非常简单.您需要做的就是包含另一个 . 以便括号表达式将表示与 .,

It gets quite simple when you know what to match in the POSIX bracket expression with [:digit:]. All you need to do is include another . so that the bracket expression would mean set of digits along with .,

sed 's/\([[:digit:].]*\)\((.*)\)/\2 \1/' file

另外你不需要提到-e，因为sed默认在BRE(基本正则表达式)模式下运行，并且带有-E 启用了 ERE(扩展正则表达式)模式.此外，\d 不是任何版本的 sed(POSIX、GNU 或 FreeBSD)用来匹配数字的有效正则表达式构造.我想它在 PCRE 库中受支持，您可以在其中使用 perl

Also you don't need to mention -e, because sed by default operates in BRE (Basic Regular Expressions) mode and with -E the ERE (Extended Regular Expression) mode is enabled. Also \d is not a valid regular expression construct used by any versions of sed (POSIX, GNU or FreeBSD) to match digits. I suppose it is supported in the PCRE library in which you could use perl

perl -lne 'print "$2 $1" if /(\d+\.?\d*).*(\([^)]*\))/' file

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