Remove first N lines on a character column in a data frame

Question

I have a data frame containing emails. There is a column named "message" that looks like this:

> > dataset$message[1]  
>[1] Message-ID:...
> 
> Date: ...
> 
> From: ...
> 
> To:...
> 
> Subject: ...
> 
> Mime-Version: ...
> 
> Content-Type:...
> 
> Content-Transfer-Encoding: ...
> 
> X-From:...
> 
> X-To: ...
> 
> X-cc:...
> 
> X-bcc: ...
> 
> X-Folder: ...
> 
> X-Origin: ...
> 
> X-FileName: ...
>  
> > Some message text

In other words, each entry contains 15 lines of headers and then the text. What I want is to remove these 15 lines from each row and be left only with the text, so that

>dataset$message[1]

looks like this:

> Some message text

Please provide a [reproducible example](http://stackoverflow.com/questions/5963269) along with expected output. Also don't forget to post your attempt that failed. Cheers — Sotos, Nov 22 '18 at 14:11
Once the data is inside the data.frame it’s too late. You want to remove it *before* it gets read into the data.frame, e.g. by providing the appropriate arguments to `read.table`. — Konrad Rudolph, Nov 22 '18 at 14:13

score 1 · Accepted Answer · answered Nov 22 '18 at 14:29

1

Something like this would work:

sub("^(?:.*\\n){15}", "", multiline_string_mail, perl = TRUE)

#[1] "Super secret message"

example data: (you should always provide usable example data)

multiline_string_mail =
"hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
hehe
Super secret message"

answered Nov 22 '18 at 14:29

Andre Elrico

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What's the `?:` inside the regex? – iod Nov 22 '18 at 15:06
1

https://stackoverflow.com/questions/36524507/notation-in-regular-expression – Andre Elrico Nov 22 '18 at 15:07
This worked for a single entry of the data frame. I put it inside a loop and applied to every entry. Thanks a lot, I'm marking it as an answer. – Eduardo Javier Huerta Yero Nov 22 '18 at 17:40

Remove first N lines on a character column in a data frame

1 Answers1