使用某些文本编辑将文本文件读入数据框的新列时出错

Question

我有一个文本文件 (0001.txt)，其中包含如下数据：

<DOC> 
<DOCNO>1100101_business_story_11931012.utf8</DOCNO> 
<TEXT> 

The Telegraph - Calcutta (Kolkata) | Business | Local firms go global
                                                                                                                           6                                                                                      Local firms go global
          JAYANTA ROY CHOWDHURY                              
    New Delhi, Dec. 31: Indian companies are stepping out of their homes to try their luck on foreign shores.         
    Corporate India invested $2.7 billion abroad in the first quarter of 2009-2010 on top of $15.9 billion in 2008-09.         
    Though the first-quarter investment was 15 per cent lower than what was invested in the same period last year, merchant banker Sudipto Bose said, It marks a confidence in a new world order where Indian businesses see themselves as equal to global players.        
    According to analysts, confidence in global recovery, cheap corporate buys abroad and easier rules governing investment overseas had spurred flow of capital and could see total investment abroad top $12 billion this year and rise to $18-20 billion next fiscal.         
    For example, Titagarh Wagons plans to expand abroad on the back of the proposed Asian railroad project.        
    We plan to travel all around the world with the growth of the railroads, said Umesh Chowdhury of Titagarh Wagons.        
    India is full of opportunities, but we are all also looking at picks abroad, said Gautam Mitra, managing director of Indian Structurals Engineering Company.         
    Mitra plans to open a holding company in Switzerland to take his business in structurals to other Asian and African countries.         
    Indian companies created 3 lakh jobs in the US, while contributing $105 billion to the US economy between 2004 and 2007, according to commerce ministry statistics. During 2008-09, Singapore, the Netherlands, Cyprus, the UK, the US and Mauritius together accounted for 81 per cent of the total outward investment.        
    Bose said, And not all of it is organic growth. Much of our investment abroad reflects takeovers and acquisitions.         
    In the last two years, Suzlon acquired Portugals Martifers stake in German REpower Systems for $122 million. McNally Bharat Engineering has bought the coal and minerals processing business of KHD Humboldt Wedag. ONGC bought out Imperial Energy for $2 billion.         
    Indias foreign assets and liabilities today add up to more than 60 per cent of its gross domestic product. By the end of 2008-09, total foreign investment was $67 billion, more than double of that at the end of March 2007.                                                                                                                                       
</TEXT> 
</DOC>

以上，所有文本数据都在文本的 HTML 代码中，即
<TEXT> 和 </TEXT>。

我想以一种有四列的方式将其读入 R 数据帧，并且数据应读取为：

Title                               Author                 Date      Text   
The Telegraph - Calcutta (Kolkata)  JAYANTA ROY CHOWDHURY  Dec. 31   Indian companies are stepping out of their homes to try their luck on foreign shores. Corporate India invested $2.7 billion abroad in the first quarter of 2009-2010 on top of $15.9 billion in 2008-09. Though the first-quarter investment was 15 percent lower than what was invested in the same period last year, merchant banker Sudipto Bose said, It marks a confidence in a new world order where Indian businesses see themselves as equal to global players.

我尝试使用 dplyr 阅读的内容如下所示：

 # read text file
 library(dplyr)
 library(readr) 

 dat <- read_csv("0001.txt") %>% slice(-8)

 # print part of data frame 
 head(dat, n=2)

在上面的代码中，我尝试从包含上述文本的文本文件中跳过前几行（这并不重要），然后将其读入数据框。

但我无法得到我正在寻找的东西，并且对我所做的事情感到困惑。

有人可以帮忙吗？

Answer 1

为了能够将数据作为数据框或表读入 R，数据需要具有由分隔符维护的一致结构。最常见的格式之一是带有逗号分隔值 (CSV) 的文件。

您正在使用的数据没有分隔符。它本质上是一个具有最小强制结构的字符串。因此，听起来这个问题与正则表达式 (regex) 和数据挖掘的关系比与将文本文件读入 R 更相关。因此，如果您经常执行此任务，我建议您研究这两件事。

除此之外，要在此示例中执行您想要的操作，我建议先将文本文件作为单个文本字符串读入 R。然后您可以使用正则表达式解析您想要的数据。以下是如何做到这一点的基本粗略草稿：

fileName <- "Path/to/your/data/0001.txt"

string <- readChar(fileName, file.info(fileName)$size)

df <- data.frame(
      Title=sub("\\s+[|]+(.*)","",string),
      Author=gsub("(.*)+?([A-Z]{2,}.*[A-Z]{2,})+(.*)","\\2",string),
      Date=gsub("(.*)+([A-Z]{1}[a-z]{2}\\.\\s[0-9]{1,2})+(.*)","\\2",string),
      Text=gsub("(.*)+([A-Z]{1}[a-z]{2}\\.\\s[0-9]{1,2})+[: ]+(.*)","\\3",string))

输出：

str(df)
'data.frame':   1 obs. of  4 variables:
 $ Title : chr "The Telegraph - Calcutta (Kolkata)"
 $ Author: chr "JAYANTA ROY CHOWDHURY"
 $ Date  : chr "Dec. 31"
 $ Text  : chr "Indian companies are stepping out of their homes to"| __truncated__

正则表达式之所以有用是因为它允许在字符串中使用非常特定的模式。缺点是当您使用不断变化的格式的字符串时。这可能意味着对所使用的正则表达式进行一些细微的调整。

Answer 2

read.table( file = ... , sep = "|") 将解决您的问题。