r - 将文本检索到数据帧的两列中的正则表达式模式匹配错误

Question

考虑以下假设数据:

x <- "There is a horror movie running in the iNox theater. : If row names are supplied of length one and the data 
frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). 
If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify 
the row names and not a column (by name or number) Can we go : Please"


y <- "There is a horror movie running in the iNox theater. If row names are supplied of length one and the data 
frame has a single row, the row.names is taken. To specify the row names and not a column. By name or number. : 
If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify 
the row names and not a column (by name or number) Can we go : Please"

z <- "There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). 
If row names are supplied of length one. : And the data frame has a single row, the row.names is taken to specify 
the row names and not a column (by name or number) Can we go : Please"

df <- data.frame(Text = c(x, y, z), row.names = NULL, stringsAsFactors = F)

您是否注意到不同位置有一个“:”。例如:

在 'x' 中，它 ( ":") 位于第一句话之后。

在 'y' 中，它 ( ":") 位于第四句之后。

在“z”中，它在第六句之后。

此外，每篇课文的最后一句前还有一个“:”。

我想要做的是，创建两列，以便:

只考虑第一个“:”，而不是最后一个。

如果前三个句子中有“:”，则将整个文本分成两列，否则，将所有文本保留在第二列中，将 'NA' 保留在第一列中。

'x' 想要的输出:

 Col1                                                        Col2 
 There is a horror movie running in the iNox theater.        If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

'y' 的通缉输出(因为在前三个句子中找不到“:”，因此):

 Col1     Col2 
 NA       There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken. To specify the row names and not a column. By name or number. : If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

就像上面 'y' 的结果一样，'z' 的想要的输出结果应该是:

  Col1    Col2
  NA      all of the text from 'z'

我想做的是:

resX <- data.frame(Col1 = gsub("\\s\\:.*$","\\1", df$Text[[1]]), 
           Col2 = gsub("^[^:]+(?:).\\s","\\1", df$Text[[1]]))

resY <- data.frame(Col1 = gsub("\\s\\:.*$","\\1", df$Text[[2]]), 
           Col2 = gsub("^[^:]+(?:).\\s","\\1", df$Text[[2]]))

resZ <- data.frame(Col1 = gsub("\\s\\:.*$","\\1", df$Text[[3]]), 
           Col2 = gsub("^[^:]+(?:).\\s","\\1", df$Text[[3]]))

然后使用 rbind 将上面的数据合并到结果数据帧“resDF”中。

问题是:

可以使用“for() 循环”或任何其他使代码更简单的方法来完成上述操作。

“y”和“z”文本的结果不是我想要的(如上所示)。

Answer 1

简短的

我的灵感来自 Rizwan's answer使我的，所以你会看到他的回答完成了我的。我不喜欢的是它在非句子开始时中断(例如 row.names - 尽管 OP 提供的文本样本没有提供任何示例，其中 row.names 在前 2 个句子中出现了 3 次来展示这一点)。我还确保捕获组/列的编号与 OP 预期的完全相同，并且始终匹配。我的回答确实是对 Rizwan 的改进。

注 1:我假设“句子”由句点/点定义，后跟至少一个水平空格 .
注 2:这适用于 PCRE 正则表达式，未经其他正则表达式风格测试，可能需要适应其他正则表达式风格才能正常工作(即 if/else、垂直空白和水平空白标记)

代码

See this code in use here

^(?(?!(?:[^:\v]*?\.\h){3,})([^:\v]*?)\s*:\s*|)(.*)$

结果

输入

There is a horror movie running in the iNox theater. : If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken. To specify the row names and not a column. By name or number. : If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). If row names are supplied of length one. : And the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

输出

第 1 场

第 1 组:There is a horror movie running in the iNox theater.

第 2 组:If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

第 2 场

第 1 组:空 - 不匹配

第 2 组:There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken. To specify the row names and not a column. By name or number. : If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

第 3 场

第 1 组:空 - 不匹配

第 2 组:There is a horror movie running in the iNox theater. If row names are supplied of length one and the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number). If row names are supplied of length one. : And the data frame has a single row, the row.names is taken to specify the row names and not a column (by name or number) Can we go : Please

解释

^断言字符串开头的位置

(?(?!(?:[^:\v]*?\.\h){3,})([^:\v]*?)\s*:\s*|)

(?(?!...)x|y) If 语句使用否定 (?!...)作为条件

(?:[^:\v]*?\.\h){3,}以下至少匹配3次

[^:\v]*?匹配集合中不存在的任何字符(不是冒号或垂直空白字符)任意次数，但尽可能少

\.\h逐字匹配点字符，后跟水平空白字符(空格或制表符)

If 语句 真 : 如果满足上述条件，请执行以下操作

([^:\v]*?)\s*:\s*

([^:\v]*?)捕获到第 1 组:任何不出现在集合中的字符(不是冒号或垂直空白字符)任意次数，但尽可能少

\s*:\s*匹配任意数量的空格字符，后跟一个冒号，然后是任意数量的空格(请注意，您可以将 * 更改为 +，如果总有至少 1 个空格字符尾随/前导冒号，在以下情况下改进匹配“句子”可能包含 : )

If 语句 假 : 不满足前面的条件，请执行以下操作: 不匹配

(.*)捕获到组 2:任何字符(当 s 标志关闭时不包括换行符)任意次数

$断言字符串末尾的位置