summary: how to read a row (not column) from a file into a vector (not a data frame)? details: I'm using $ lsb_release -ds Linux Mint Debian Edition $ uname -rv 3.0.0-1-amd64 #1 SMP Sun Jul 24 02:24:44 UTC 2011 $ R --version R version 2.14.1 (2011-12-22) I'm new to R (having previously used it only for graphics), but have worked in many other languages. I've got a CSV file from which I'd like to read the values from a single *row* into a vector. E.g., for a file such that $ head -n 2 ~/data/foo.csv | tail -n 1 5718,0.3,0.47,0,0,0,0,0,0,0,0,0.08,0.37,0,0,0.83,1.55,0,0,0,0,0,0,0,0,0,0.00,2.48,2.33,0.17,0,0,0,0,0,0,0.00,10.69,0.18,0,0,0,0 I'd like to be able to populate a vector 'v' s.t. v[1]=5718, ... v[43]=0 I can't seem to do that with, e.g., read.csv(...) or scan(...), both of which seem column-oriented. What am I missing?
Tom Roche wrote> > summary: how to read a row (not column) from a file into a vector (not a > data frame)? > > details: > > I'm using > > $ lsb_release -ds > Linux Mint Debian Edition > $ uname -rv > 3.0.0-1-amd64 #1 SMP Sun Jul 24 02:24:44 UTC 2011 > $ R --version > R version 2.14.1 (2011-12-22) > > I'm new to R (having previously used it only for graphics), but have > worked in many other languages. I've got a CSV file from which I'd like to > read the values from a single *row* into a vector. E.g., for a file such > that > > $ head -n 2 ~/data/foo.csv | tail -n 1 > 5718,0.3,0.47,0,0,0,0,0,0,0,0,0.08,0.37,0,0,0.83,1.55,0,0,0,0,0,0,0,0,0,0.00,2.48,2.33,0.17,0,0,0,0,0,0,0.00,10.69,0.18,0,0,0,0 > > I'd like to be able to populate a vector 'v' s.t. v[1]=5718, ... v[43]=0 > > I can't seem to do that with, e.g., read.csv(...) or scan(...), both of > which seem column-oriented. What am I missing? > > ______________________________________________ > R-help@ mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >Hello, ?readLines If you want the 2nd line it's fast, if you have a large file, cycle through. Rui Barradas -- View this message in context: http://r.789695.n4.nabble.com/newbie-read-row-from-file-into-vector-tp4243952p4244038.html Sent from the R help mailing list archive at Nabble.com.
On 11-12-29 3:51 PM, Tom Roche wrote:> > summary: how to read a row (not column) from a file into a vector (not a data frame)? > > details: > > I'm using > > $ lsb_release -ds > Linux Mint Debian Edition > $ uname -rv > 3.0.0-1-amd64 #1 SMP Sun Jul 24 02:24:44 UTC 2011 > $ R --version > R version 2.14.1 (2011-12-22) > > I'm new to R (having previously used it only for graphics), but have worked in many other languages. I've got a CSV file from which I'd like to read the values from a single *row* into a vector. E.g., for a file such that > > $ head -n 2 ~/data/foo.csv | tail -n 1 > 5718,0.3,0.47,0,0,0,0,0,0,0,0,0.08,0.37,0,0,0.83,1.55,0,0,0,0,0,0,0,0,0,0.00,2.48,2.33,0.17,0,0,0,0,0,0,0.00,10.69,0.18,0,0,0,0 > > I'd like to be able to populate a vector 'v' s.t. v[1]=5718, ... v[43]=0 > > I can't seem to do that with, e.g., read.csv(...) or scan(...), both of which seem column-oriented. What am I missing?Those are both column oriented, but you can change the result to a vector after reading it. For example, x <- read.csv("foo.csv", nrow=1) x <- as.numeric(x[1,]) # convert to numeric vector If you don't want the first row, use skip=<something> in the read.csv call. Duncan Murdoch
Look into connection objects, which let you open a file or other
readable sort of thing and read it piece by piece. E.g., the
following function opens your file (making a "file connection"),
skips some lines, reads the desired line into a character object,
then reads from that character object (as a "text connection")
to make a numeric object:
f <- function (fileName, lineNumber, ...)
{
connection <- file(fileName, "rt")
on.exit(close(connection))
if (lineNumber > 1) {
readLines(connection, n = lineNumber - 1)
}
lineText <- readLines(connection, n = 1)
scan(textConnection(lineText), ...)
}
Here is a self-contained example:
> tfile <- tempfile()
> cat(file=tfile, sep="\n", "A data file with a header
line",
+ "101;102;103", "104,105",
"106/107/108")> cat(readLines(tfile), sep="\n") # look at text in file
A data file with a header line
101;102;103
104,105
106/107/108> f(tfile, lineNumber=3, sep=",") # read third line as comma
separated numbers
Read 2 items
[1] 104 105
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf Of Tom Roche
> Sent: Thursday, December 29, 2011 12:51 PM
> To: r-help at r-project.org
> Subject: [R] [newbie] read row from file into vector
>
>
> summary: how to read a row (not column) from a file into a vector (not a
data frame)?
>
> details:
>
> I'm using
>
> $ lsb_release -ds
> Linux Mint Debian Edition
> $ uname -rv
> 3.0.0-1-amd64 #1 SMP Sun Jul 24 02:24:44 UTC 2011
> $ R --version
> R version 2.14.1 (2011-12-22)
>
> I'm new to R (having previously used it only for graphics), but have
worked in many other languages.
> I've got a CSV file from which I'd like to read the values from a
single *row* into a vector. E.g.,
> for a file such that
>
> $ head -n 2 ~/data/foo.csv | tail -n 1
>
5718,0.3,0.47,0,0,0,0,0,0,0,0,0.08,0.37,0,0,0.83,1.55,0,0,0,0,0,0,0,0,0,0.00,2.48,2.33,0.17,0,0,0,0,0,
> 0,0.00,10.69,0.18,0,0,0,0
>
> I'd like to be able to populate a vector 'v' s.t. v[1]=5718,
... v[43]=0
>
> I can't seem to do that with, e.g., read.csv(...) or scan(...), both of
which seem column-oriented.
> What am I missing?
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
The scan function can be used to read a single row. If your file has multiple rows you can use the skip and nlines arguments to determine which row to read. With the what argument sent to a single item (a number or string depending on which you want) it will read each element on that row into a vector. If you want to do more of the hard work yourself you can read in a whole line as a single string using the readLines function then use the strsplit (or possibly better, tools from the gsubfun package) to split that string into a vector (the unlist function may also be of help). -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow at imail.org 801.408.8111> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of Tom Roche > Sent: Thursday, December 29, 2011 1:51 PM > To: r-help at r-project.org > Subject: [R] [newbie] read row from file into vector > > > summary: how to read a row (not column) from a file into a vector (not > a data frame)? > > details: > > I'm using > > $ lsb_release -ds > Linux Mint Debian Edition > $ uname -rv > 3.0.0-1-amd64 #1 SMP Sun Jul 24 02:24:44 UTC 2011 > $ R --version > R version 2.14.1 (2011-12-22) > > I'm new to R (having previously used it only for graphics), but have > worked in many other languages. I've got a CSV file from which I'd like > to read the values from a single *row* into a vector. E.g., for a file > such that > > $ head -n 2 ~/data/foo.csv | tail -n 1 > 5718,0.3,0.47,0,0,0,0,0,0,0,0,0.08,0.37,0,0,0.83,1.55,0,0,0,0,0,0,0,0,0 > ,0.00,2.48,2.33,0.17,0,0,0,0,0,0,0.00,10.69,0.18,0,0,0,0 > > I'd like to be able to populate a vector 'v' s.t. v[1]=5718, ... > v[43]=0 > > I can't seem to do that with, e.g., read.csv(...) or scan(...), both of > which seem column-oriented. What am I missing? > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code.