From gsee000 at gmail.com  Wed Dec 19 14:37:53 2012
From: gsee000 at gmail.com (G See)
Date: Wed, 19 Dec 2012 07:37:53 -0600
Subject: [Rd] read.csv reads more rows than indicated by wc -l
Message-ID: <CA+xi=qYXfHwKch5a3GwQ6QR4923KU2TLrWmM2xt+AQLtLHy8Yg@mail.gmail.com>

When I have a csv file that is more than 6 lines long, not including
the header, and one of the fields is blank for the last few lines, and
there is an extra comma on of the lines with the blank field,
read.csv() makes creates an extra line.

I attached an example file; I'll also paste the contents here:

A,apple
A,orange
A,orange
A,orange
A,orange
A,,,
A,,

-----
wc -l reports that this file has 7 lines

R> system("wc -l test.csv")
7 test.csv

But, read.csv reads 8.

R> read.csv("test.csv", header=FALSE, stringsAsFactors=FALSE)
  V1     V2
1  A  apple
2  A orange
3  A orange
4  A orange
5  A orange
6  A
7
8  A

If I increase the number of commas at the end of the line, it
increases the number of rows.

This R command to read a 7 line csv:

read.csv(header=FALSE, text="A,apple
A,orange
A,orange
A,orange
A,orange
A,,,,,
A,,")

will produce this:

  V1     V2
1  A  apple
2  A orange
3  A orange
4  A orange
5  A orange
6  A
7
8
9  A


But if the file has fewer than 7 lines, it doesn't increase the number of rows.

This R command to read a 6 line csv:
read.csv(header=FALSE, text="A,apple
A,orange
A,orange
A,orange
A,,,,,
A,,")

will produce this:

  V1     V2 V3 V4 V5 V6
1  A  apple NA NA NA NA
2  A orange NA NA NA NA
3  A orange NA NA NA NA
4  A orange NA NA NA NA
5  A        NA NA NA NA
6  A        NA NA NA NA



Is this intended behavior?

Thanks,
Garrett See

R> version
               _
platform       x86_64-pc-linux-gnu
arch           x86_64
os             linux-gnu
system         x86_64, linux-gnu
status
major          2
minor          15.2
year           2012
month          10
day            26
svn rev        61015
language       R
version.string R version 2.15.2 (2012-10-26)
nickname       Trick or Treat

R> sessionInfo()
R version 2.15.2 (2012-10-26)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=C                 LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base


[Rd] read.csv reads more rows than indicated by wc -l
G See