Remove a section from Corpus - r

Question

I have a quanteda corpus of hundreds of documents. How do I remove specific sections - like the abstract and footnotes etc. Otherwise, I am faced with doing it manually. Thanks
As requested, here is a text example. It is from a regular journal article. It shows the Meta data, then the abstract, then keywords, then introduction, then author contact details, then body of article, then Note, then Disclosure statement, then Notes on contributors, then references. I would like to remove everything apart from the introduction and body of the article. I would also like to remove the author name and Journal title - which are repeated throughout
" Behavioral Sciences of Terrorism and Political Aggression
ISSN: 1943-4472 (Print) 1943-4480 (Online) Journal homepage: http://www.tandfonline.com/loi/rirt20
Sometimes they come back: responding to
American foreign fighter returnees and other
Elusive threats
Christopher J. Wright
To cite this article: Christopher J. Wright (2018): Sometimes they come back: responding to
American foreign fighter returnees and other Elusive threats, Behavioral Sciences of Terrorism and
Political Aggression, DOI: 10.1080/19434472.2018.1464493
To link to this article: https://doi.org/10.1080/19434472.2018.1464493
Published online: 23 Apr 2018.
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Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=rirt20
"
"BEHAVIORAL SCIENCES OF TERRORISM AND POLITICAL AGGRESSION, 2018
https://doi.org/10.1080/19434472.2018.1464493
Sometimes they come back: responding to American foreign
fighter returnees and other Elusive threats
Christopher J. Wright
Department of Criminal Justice, Austin Peay State University, Clarksville, TN, USA
ABSTRACT ARTICLE HISTORY
Much has been made of the threat of battle hardened jihadis from Received 8 January 2018
Islamist insurgencies, especially Syria. But do Americans who Accepted 10 April 2018
return home after gaining experience fighting abroad pose a
KEYWORDS
greater risk than homegrown jihadi militants with no such Terrorism; foreign fighters;
experience? Using updated data covering 1990–2017, this study domestic terrorism;
shows that the presence of a returnee decreases the likelihood homegrown terrorism;
that an executed plot will cause mass casualties. Plots carried out lone-wolf; homeland security
Introduction: being afraid. Being a little afraid
How great of a threat do would-be jihadis pose to their home country? And do those who
return home after gaining experience fighting abroad in Islamist insurgencies or attending
terror training camps pose a greater risk than other jihadi militants? The fear, as first outlined
by Hegghammer (2013), is two-fold. First, individuals that have gone abroad to fight might
CONTACT Christopher J. Wright wrightc#apsu.edu Department of Criminal Justice, Austin Peay State University,
Clarksville, TN 37043, USA
© 2018 Society for Terrorism Research
"
"2 C. J. WRIGHT
Many of the earliest studies on Western foreign fighters suggested that those who
returned were in fact more deadly than those with no experience fighting in Islamist insur-
gencies. Hegghammer’s (2013) analysis suggested that these foreign fighter returnees
were a greater danger than when they left. Likewise, Byman (2015), Nilson (2015),
Kenney (2015), and Vidno (2011) came to similar conclusions while offering key insights
into the various mechanisms linking foreign fighting with successful plot execution and
greater mass casualties.
Other studies came to either mixed conclusions or directly contradicted the earlier find-
ings. Adding several years of data to Hegghammer’s (2013) earlier study, Hegghammer
"
" BEHAVIORAL SCIENCES OF TERRORISM AND POLITICAL AGGRESSION 3
for them to form the types of large, local networks that would be necessary to carry out a
large-scale attack without attracting the attention of security services’ (p. 92).
"
Note
1. Charges were brought against Noor Zahi Salman, the widow of the Omar Mateen who carried
out the June, 2016 attack against the Pulse Nightclub in Orlando, Florida (US Department of
Justice., 2017a, January 17). However, in March of 2018 a jury acquitted her of the charges that
she had foreknowledge of the attack.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes on contributors
Christopher J. Wright, Ph.D., is an Assistant Professor at Austin Peay State University where he
teaches in the Homeland Security Concentration.
ORCID
Christopher J. Wright http://orcid.org/0000-0003-0043-6616
References
Byman, D. (2015). The homecomings: What happens when Arab foreign fighters in Iraq and Syria
return? Studies in Conflict & Terrorism, 38(8), 581–602.
Byman, D. (2016). The Jihadist returnee threat: Just how dangerous? Political Science Quarterly, 131(1),
69–99.
Byman, D., & Shapiro, J. (2014). Be afraid. Be a little afraid: The threat of terrorism from Western foreign
fighters in Syria and Iraq. Foreign Policy at Brookings. Washington, DC: Brookings. Retrieved from
https://www.brookings.edu/wp-content/uploads/2016/06/Be-Afraid-web.pdf

Answer 1

The approach
The key here is to determine the regular markers that precede each section, and then to use them as tags in a call to corpus_segment(). It's the tags that will need tweaking, based on their degree of regularity across documents.
Based on what you supplied above, I pasted that into a plain text file that I named example.txt. This code extracted the Introduction and what I think is the body of the article, but for that I had to decide a tag that marked its ending. Below, I used "Disclosure Statement". So:
library("quanteda")
crp <- readtext::readtext("~/tmp/example.txt") %>%
corpus()
pat <- c("\nIntroduction?", "\nCONTACT", "©", "\nDisclosure statement")
crpextracted <- corpus_segment(crp, pattern = pat)
summary(crpextracted)
## Corpus consisting of 4 documents:
##
## Text Types Tokens Sentences pattern
## example.txt.1 62 74 5 Introduction:
## example.txt.2 18 21 2 CONTACT
## example.txt.3 156 253 11 ©
## example.txt.4 101 180 19 Disclosure statement
##
## Source: /Users/kbenoit/Dropbox (Personal)/GitHub/quanteda/quanteda/* on x86_64 by kbenoit
## Created: Fri Jul 6 19:51:01 2018
## Notes: corpus_segment.corpus(crp, pattern = pat)
When you examine the text in the "Introduction:" tagged segment, you can see that everything from that string until the next tag was extracted to that as a new document:
corpus_subset(crpextracted, pattern == "\nIntroduction:") %>%
texts() %>% cat()
## being afraid. Being a little afraid
##
## How great of a threat do would-be jihadis pose to their home country? And do those who
##
## return home after gaining experience fighting abroad in Islamist insurgencies or attending
##
## terror training camps pose a greater risk than other jihadi militants? The fear, as first outlined
##
## by Hegghammer (2013), is two-fold. First, individuals that have gone abroad to fight might
How to remove pdf junk
All pdf conversions produce unwanted junk such as running headers, footers, etc. Here's how to remove them. (Note: You will want to do this before the step above.) How to construct the toreplace pattern? You will need to understand something about regular expressions, and use some experimentation.
library("stringr")
toreplace <- '\\n*\" \" BEHAVIORAL SCIENCES OF TERRORISM AND POLITICAL AGGRESSION,{0,1} \\d+\\n*'
texts(crp) <- str_replace_all(texts(crp), regex(toreplace), "")
cat(texts(crp))
To demonstrate this on a section from your example:
# demonstration
x <- '
" " BEHAVIORAL SCIENCES OF TERRORISM AND POLITICAL AGGRESSION 3
'
str_replace_all(x, regex(toreplace), "")
## [1] ""