如何在 R 中使用条件将 2 行或更多行文本合并为 1 行

Question

我想将 Thunderbird Mozilla 的 Sent 文件读入 R。 有时必须将 2 条或更多条线放在 1 条线上。 这些是以"，"逗号结尾的行 例如：

From: Frans  <[e-mail]>
Subject: volledig overzicht beschikbaar
To: [e-mail], [e-mail], [e-mail],
[e-mail], [e-mail], [e-mail],
[e-mail]
Date: Mon, 21 Mar 2016 14:17:09 +0100

合并后：

From: Frans  <[e-mail]>
Subject: volledig overzicht beschikbaar
To: [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail],  [e-mail]
Message-ID: <[e-mail]>
Date: Mon, 21 Mar 2016 14:17:09 +0100

Answer 1

我不会只依赖逗号。使用grep您可以识别带有To:标记的行并粘贴所有行，直到具有以下标记的行Message-ID:/Date:。

cleanHeader <- function(x) {
line.to <- grep("^To", header)
line.next <- grep("^Date|^Mess", header)[1]
new.to <- paste(header[line.to:(line.next - 1)], collapse="")
c(header[1:(line.to - 1)], new.to, header[line.next:length(header)])
}

结果

cleanHeader(header1)  
[1] "From: Frans  <[e-mail]>"
[2] "Subject: volledig overzicht beschikbaar"
[3] "To: [e-mail], [e-mail], [e-mail], [e-mail], 
[e-mail], [e-mail], [e-mail]"
[4] "Date: Mon, 21 Mar 2016 14:17:09 +0100"                                                   
cleanHeader(header2)
[1] "From: Frans  <[e-mail]>"                                                  
[2] "Subject: volledig overzicht beschikbaar"
[3] "To: [e-mail], [e-mail], [e-mail], [e-mail], 
[e-mail], [e-mail],  [e-mail]"
[4] "Message-ID: <[e-mail]>"
[5] "Date: Mon, 21 Mar 2016 14:17:09 +0100"

<小时 />

数据：

tmp <- tempfile()
cat("From: Frans  <[e-mail]>
Subject: volledig overzicht beschikbaar
To: [e-mail], [e-mail], [e-mail],
[e-mail], [e-mail], [e-mail],
[e-mail]
Date: Mon, 21 Mar 2016 14:17:09 +0100", file=tmp, sep="n")
header1 <- readLines(tmp)
cat("From: Frans  <[e-mail]>
Subject: volledig overzicht beschikbaar
To: [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail],  [e-mail]
Message-ID: <[e-mail]>
Date: Mon, 21 Mar 2016 14:17:09 +0100", file=tmp, sep="n")
header2 <- readLines(tmp)