CODEWITHSUNDEEP
rappend
Regulus
Regulus

Reputation: 177

R - Reading text in a file and appending it to another

I am running RStudio 3.2.3 on Windows 7. I need to read certain text in a text file. The code below successfully appends from line 1 to 24 in the original file to the new file. The lines I need to append into the new file always starts with "DATE ACQUIRED = ". Can I search for that line (line 23), just read the date on it, and append the date to the file? If I could append it to a spreadsheet that would be great. 

con <- file("LC80140332015238LGN00_MTL.txt") 
        x <- readLines(con,24) 
        unlink("data") 
        write(x,file="myMTLfile2.txt",append=TRUE)[/CODE]

Upvotes: 0

Views: 1078

Answers (1)

romants
romants

Reputation: 3648

Simple parsing using grep and sub should work just fine

lines <- readLines("LC80140332015238LGN00_MTL.txt")
# get lines with DATE_ACQUIRED
matched_lines <- lines[which(grepl("DATE_ACQUIRED", lines))]
# extract date
date_acquired <- sub(".*(\\d{4}-\\d{2}-\\d{2}).*", "\\1", matched_lines)
write(date_acquired, "myMTLfile2.txt", append=TRUE)

You might need to change the regex for date parsing if you have dates in different formats.

Upvotes: 1

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