CODEWITHSUNDEEP
pythonr
Ggplot
Ggplot

Reputation: 31

How do I delete rows from a text file in R?

I have a text file with data line items that looks like:

  1. 1~123~JJJ
  2. 2~223~AAA
  3. 3~444~LLL
  4. 4~567~PPP
  5. 5~785~QQQ

I'd like to delete the lines that contain the following values:(I have another text file that has these values that need to be deleted) PPP QQQ

To end up with:

  1. 1~123~JJJ
  2. 2~223~AAA
  3. 3~444~LLL

I have never used R and would like to know if there is a way to have this done. If it can be done in a faster way in Python, please let me know. I am open to options.

Upvotes: 2

Views: 663

Answers (3)

GLaw1300
GLaw1300

Reputation: 205

I am not familiar with R, but here's how I'd do it in python

with open("yourfile.txt", "r") as f:
    lines = f.readlines()
with open("yourfile.txt", "w") as f:
    for line in lines:
        if not line.__contains__("string to delete"):
            f.write(line)

EDIT: for this to work with reading another file with all of the strings to exclude, you'd do the following:

with open("to be deleted.txt", "r") as f:
    parts = f.readlines()
with open("yourfile.txt", "r") as f:
    lines = f.readlines()
with open("yourfile.txt", "w") as f:
    for line in lines:
        for part in parts:
            if not part in line:
                f.write(line)

Upvotes: 2

Tim Biegeleisen
Tim Biegeleisen

Reputation: 521429

You could use a combination of readLines and grepl, followed by writeLines:

conn <- file("path/to/input.txt")
lines <- readLines(conn)
close(conn)
lines <- lines[grepl("^(?!.*\\b(?:PPP|QQQ)\\b).*$", lines, perl=TRUE)]

conn <- file("path/to/input.txt", "w")  # assuming you want to write to the same file
writeLines(lines, conn)
close(conn)

Upvotes: 3

Jilber Urbina
Jilber Urbina

Reputation: 61164

You can use grep for integer indexing

> df[-grep("PPP|QQQ", df$V1), , drop=FALSE]
         V1
1 1~123~JJJ
2 2~223~AAA
3 3~444~LLL

Where df is a data.frame:

df <- read.table(text="1~123~JJJ
2~223~AAA
3~444~LLL
4~567~PPP
5~785~QQQ", header=FALSE, stringsAsFactors=FALSE)

Upvotes: 2

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