Reading files from folder and storing them to dataframe in R - r

Question

My goal eventually is to build a classifier -- something like a spam detector.
I am not sure however how to read the text files that contain the text that will feed the classifier and store it to a dataframe.
So suppose that I have assembled in a folder text files -- raw text initially stored in a Notepad and then saved from it in a txt file-- whose names are indicative of their content, e.g. xx_xx_xx__yyyyyyyyyyy_zzzzz, where xx will be numbers representing a date, yyyyyyyyy will be a character string representing a theme and zzzz will be a character string representing a source. yyyyyyyyyyy and zzzzzzz will be of variable lengths.
My objective would be to create a function that would loop through the files, read them, store the information contained in their names in separate columns of a dataframe --e.g. "Date", "Theme", "Source" -- and the text content in a fourth column (e.g. "Content").
Any ideas how this could be achieved?
Your advice will be appreciated.

Answer 1

Hi here is a possible answer, I'm storing results in a list instead of a data frame but you can convert from one to the other by using do.call(rbind.data.frame, result)
require(stringr)
datawd<-"C:/my/path/to/folder/" # your data directory
listoffiles<-list.files(str_c(datawd)) # list of files
listoffiles<-listoffiles[grep(".txt",listoffiles)] # only extract .txt files
my_paths<-str_c(datawd,listoffiles) # vector of path
# the following works with windows only
progress<-winProgressBar(title = "loading text files",
label = "progression %",
min = 0,
max = length(my_paths),
initial = 0,
width = 400)
#000000000000000000000000000000000000000 loop
for (i in 1:length(chemins)){
result<-list()
setWinProgressBar(progress,i,label=listoffiles[i])
the_date<-sapply(strsplit(listoffiles[i],"_"),"[[",1)
the_theme<-sapply(strsplit(listoffiles[i],"_"),"[[",2)
the_source<-sapply(strsplit(listoffiles[i],"_"),"[[",3)
# open connexion with read
con <- file(my_paths[i], open = "r")
# readlines returns an element per line, here I'm concatenating all,
#you will do what you need....
the_text<- str_c(readLines(con,warn = FALSE))
close(con) # closing the connexion
result[[i]]<-list()
result[[i]]["date"]<-the_date
result[[i]]["source"]<-the_source
result[[i]]["theme"]<-the_theme
result[[i]]["text"]<-the_text
}
#000000000000000000000000000000000000000 end loop