ack ：获取第 10 个（或更大的第 n 个）匹配/捕获组

Question

我想我可能刚刚搜索错了，但我没有找到任何答案。如果有重复，请告诉我，我可以将其删除。

问题背景

我正在使用ack（链接），它在引擎盖下有 Perl 5，来获取 n-gram - 特别是高阶 n-gram。我可以使用我知道的语法（基本上最多$9）获得最多 9 克，但我无法获得 10 克。使用$10只是给了我$1一个0之后。之类的东西$(10)，并${10}没有解决问题。我对使用语言建模工具包的解决方案不感兴趣，我想使用ack.

我使用的一个数据集是马克吐温的全集

( wget http://www.gutenberg.org/cache/epub/3200/pg3200.txt && mv pg3200.txt TWAIN_Mark_complete_orig.txt).

我已经解析干净了（请参阅文章末尾的解析注释）并将解析结果保存为TWAIN_Mark_complete_parsed.txt.

我从 2 克中得到了很好的结果，代码和部分结果是

time cat TWAIN_Mark_complete_parsed.txt | \
    ack '(\S+) +(?=(\S+) +)' \
    --output '$1 $2' | \
    sort | uniq -c | \
    sort -rn > Twain_2grams.txt
## `time` info not shown
$ head -n 2 Twain_2grams.txt
  18176 of the
  13288 in the

一直到 9 克，与

time cat TWAIN_Mark_complete_parsed.txt | \
    ack '(\S+) (?=(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+))' \
    --output '$1 $2 $3 $4 $5 $6 $7 $8 $9' | \
    sort | uniq -c | sort -rn > Twain_9grams.txt
## time info not shown
$ head -n 2 Twain_9grams.txt
     17 to mrs jane clemens and mrs moffett in st
     17 mrs jane clemens and mrs moffett in st louis

（注意，我对ack命令进行元编程，而不仅仅是键入每个命令。）

问题/我的尝试

我第一次尝试 10 克，以及结果，是

time cat TWAIN_Mark_complete_parsed.txt | \
    ack '(\S+) (?=(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+))' \
    --output '$1 $2 $3 $4 $5 $6 $7 $8 $9 $10' | \
    sort | uniq -c | sort -rn > Twain_10grams.txt

$ head -n 2 Twain_10grams.txt
     17 to mrs jane clemens and mrs moffett in st to0
     17 mrs jane clemens and mrs moffett in st louis mrs0

为了更好地了解正在发生的事情，

参见 这个 SO 答案（和这个评论）有关如何通过逐字差异突出显示来获得彩色差异的详细信息。基本上apt或yum为colordiff，然后pip为diff-highlight。

使用$(10)而不是$10将输出的前两行作为

     17 to mrs jane clemens and mrs moffett in st $(10)
     17 mrs jane clemens and mrs moffett in st louis $(10)

（两分钟后）。

使用${10}而不是$10将输出的前两行作为

     17 to mrs jane clemens and mrs moffett in st ${10}
     17 mrs jane clemens and mrs moffett in st louis ${10}

我的想法就到此为止。

预期/期望输出

注意这里是一个统计（非常非零和有限的）实际输出是从这里显示的不同的可能性。9-gram 的前两个结果不是不同的单词序列。通过查看前 10 个最常见的 9-gram 可以找到更常见的 10-gram 的其他可能部分 - 使用head代替head -n 2。即便如此，我相当肯定，即使这样也不能保证我们有两个最频繁的 10 克。但是，我希望我已经足够清楚地说明了我想要完成的任务。

17 to mrs jane clemens and mrs moffett in st louis
3 mrs jane clemens and mrs moffett in st louis honolulu

编辑我已经发现另一组将预期输出更改为（可能不是实际输出，而是将其从我之前使用的简单模型更改的一组。）

     17 to mrs jane clemens and mrs moffett in st louis
      7 happiness in his home had been wounded and bruised almost

那将是head -n 2我一直用来显示我得到什么样的结果的。

我不想通过我将在这里使用的相同过程获得它。

$ grep -o "to mrs jane clemens and mrs moffett in st [^ ]\+" \
   TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
     17 to mrs jane clemens and mrs moffett in st louis

$ grep -o "mrs jane clemens and mrs moffett in st louis [^ ]\+" \
   TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      3 mrs jane clemens and mrs moffett in st louis honolulu
      2 mrs jane clemens and mrs moffett in st louis san
      2 mrs jane clemens and mrs moffett in st louis no
      2 mrs jane clemens and mrs moffett in st louis 224
      1 mrs jane clemens and mrs moffett in st louis wash
      1 mrs jane clemens and mrs moffett in st louis wailuku
      1 mrs jane clemens and mrs moffett in st louis virginia
      1 mrs jane clemens and mrs moffett in st louis the
      1 mrs jane clemens and mrs moffett in st louis sept
      1 mrs jane clemens and mrs moffett in st louis on
      1 mrs jane clemens and mrs moffett in st louis hartford
      1 mrs jane clemens and mrs moffett in st louis carson

编辑用于查找较新的第二位频率的代码是

$ grep -o "[^ ]\+ happiness in his home had been wounded and bruised" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      6 shelley's happiness in his home had been wounded and bruised
      1 his happiness in his home had been wounded and bruised
$ grep -o "shelley's happiness in his home had been wounded and [^ ]\+" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      6 shelley's happiness in his home had been wounded and bruised
$ grep -o "happiness in his home had been wounded and bruised [^ ]\+" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      7 happiness in his home had been wounded and bruised almost
$ grep -o "in his home had been wounded and bruised almost [^ ]\+" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      7 in his home had been wounded and bruised almost to
$ grep -o "his home had been wounded and bruised almost to [^ ]\+" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      7 his home had been wounded and bruised almost to death
$ grep -o "home had been wounded and bruised almost to death [^ ]\+" TWAIN_Mark_complete_parsed.txt | sort | uniq -c | sort -rn
      1 home had been wounded and bruised almost to death thirdly
      1 home had been wounded and bruised almost to death secondly
      1 home had been wounded and bruised almost to death it
      1 home had been wounded and bruised almost to death fourthly
      1 home had been wounded and bruised almost to death first
      1 home had been wounded and bruised almost to death fifthly
      1 home had been wounded and bruised almost to death and

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从评论中编辑

@Inian 发表了很棒的评论：

这记录在发行说明中 - github.com/beyondgrep/ack3/blob/dev/RELEASE-NOTES.md -您现在仅限于以下变量：$1 到 $9、$、$.、$&、$` , $' 和 $+_

对于未来的人，我正在放一个版本，今天存档，RELEASE-NOTES

在man对页面ack确实有行

$1 through $9
The subpattern from the corresponding set of capturing parentheses.
If your pattern is "(.+) and (.+)", and the string is "this and that',
then $1 is "this" and $2 is "that".

但我希望有办法获得更高的数字。根据来自 的信息RELEASE-NOTES，这种希望似乎已基本消失。

但是，我仍然想知道是否有人有解决方法或技巧，无论是使用ack还是使用任何更“标准”的 *NIX 类型终端工具。我的偏好依次是perl、grep、awk、sed。如果有类似的东西ack（即只是命令行解析，而不是基于 NLP 工具包的解决方案），我也对此感兴趣。

我认为最好将此作为一个新问题提出。如果你在这里回答，太好了。如果我最终发布了一个新问题，我会将链接放在这里：目前，这只是指向同一问题的链接。

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解析笔记

为了让我的语料库准备好进行 n-gram 分析，这是我的解析。

     17 to mrs jane clemens and mrs moffett in st $(10)
     17 mrs jane clemens and mrs moffett in st louis $(10)

是的，这一切都可以在一行上（并且没有尾随 && :），但是这样可以更容易阅读并解释我为什么要做我正在做的事情。

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系统详情

     17 to mrs jane clemens and mrs moffett in st ${10}
     17 mrs jane clemens and mrs moffett in st louis ${10}