Looping over a text collection to extract subchapters - r

Question

As a continuation of my example here, I`m now confronted with the problem that I want to extract subchapters for all documents in my document collection in R for further Text Mining. This is my sample data:
doc_title <- c("Example.docx", "AnotherExample.docx")
text <- c("One morning, when Gregor Samsa woke from troubled dreams, he found himself transformed in his bed into a horrible vermin.
1 Introduction
He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections.
1.1 Futher
The bedding was hardly able to cover it and seemed ready to slide off any moment.", "2.2 Futher Fuhter
'What's happened to me?' he thought. It wasn't a dream. His room, a proper human room although a little too small, lay peacefully between its four familiar walls.")
doc_corpus <- data.frame(doc_title, text)
This is the function to divide the text into subchapters:
divideInto_subchapters <- function(doc_corpus){
corpus_text <- doc_corpus$text
# Replace lines starting with N.N.N+ with space
corpus_text <- gsub("\\R\\d+(?:\\.\\d+){2,}\\s+[A-Z].*\\R?", " ", corpus_text, perl=TRUE)
# Split into IDs and Texts
data <- str_match_all(corpus_text, "(?sm)^(\\d+(?:\\.\\d+)?\\s+[A-Z][^\r\n]*)\\R(.*?)(?=\\R\\d+(?:\\.\\d+)?\\s+[A-Z]|\\z)")
# Get the chapter ID column
chapter_id <- trimws(data[[1]][,2])
# Get the text ID column
text <- trimws(data[[1]][,3])
# Create the target DF
corpus <- data.frame(doc_title, chapter_id, text)
return(corpus)
}
Now I want to loop over all elements in my doc_corpus and divide all plain text into subchapters. This is what I tried out so far:
subchapter_corpus <- data.frame()
for (i in 1:nrow(doc_corpus)) {
temp_corpus <- divideInto_subchapters(doc_corpus[i])
subchapter_corpus <- rbind(subchapter_corpus, temp_corpus)
}
Unfortunately, this returns an empty data frame. What am I getting wrong here? Any help is highly appreciated.
My expected output for the first df row looks like this:
doc_title <- c("Example.docx")
chapter_id <- (c("1 Introduction"))
text <- (c("He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections.""))
chapter_one_df <- data.frame(doc_title, chapter_id, text)

Answer 1

So, for me the loop gave me "subscript out of bounds" until I changed doc_corpus[i] to doc_corpus[i, ]. With that change, I do get one row in the resulting data frame.
However, it's only chapter_id "2.2 Further Fuhter." It seems to be missing "1.1 Futher."
If it's a matter of the regex, then man it would sure help if you commented what you were doing with it! :)
Feel free to comment and I'll amend my answer as needed till it's helpful. Not sure if that's how it works, but this is only my 3rd day of answering questions on SO.