This document discusses creating a table from a list of files by extracting text between delimiters. It defines file paths and an empty data frame to store results. Files are read and text is collapsed. A regular expression is used to find text between "<div class="nota">" and "</div>" tags, and this note text is added to the data frame along with the file name. The process repeats to populate the data frame with file names and note text extracted from multiple files.

1. R- Create a table from a list of files (part I)

2. R- Create a table from a list of files (part I)
• Let’s define paths:
sources <- c(
"C:/Users/Gaby/Documents/4.R/webmining/sociedad/")
Then let’s define a table where the data will be saved:
df<-data.frame(
fileName=NULL,
nota=NULL)
df$fileName <- as.character(df$fileName)
df$nota <- as.character(df$nota)

3. • Let’s read the files stored in the path
files_dep<-list.files(path = sources, pattern = NULL, all.files = TRUE,
full.names = FALSE, recursive = FALSE,
ignore.case = FALSE, include.dirs = FALSE, no.. = TRUE)
Let’s asume our text is like:
'anflkanfklnlka <div class="nota"> esta es la nota </div> akjbfkab‘
So we want to get only ‘esta es la nota’.
If we define:
empieza<-'<div class="nota">'
termina<-'</div>‘
We can use:
paste0("(^.*", empieza, ")(.*?)(", termina, ".*)$")
In order to achieve:
"(^.*<div class="nota">)(.*?)(</div>.*)$"

4. text<-readLines(paste0(sources, files_dep[1]),encoding="UTF-8")
j=1
for (i in files_dep) {
j=j+1
print(i)
text<-readLines(i,encoding="UTF-8")
aa<-paste(text, collapse=' ')
if (grepl(empieza,aa) & grepl(termina,aa)) {
nota=gsub(paste0("(^.*", empieza, ")(.*?)(", termina, ".*)$"), "2", aa)
df<-rbind(df, data.frame(clase=clases[ci], fileName=i, nota=nota))
print(clases[ci])
}
Now df is a table with 3 variables:clase, fileName and nota.