Simple question about error on CSV import

[esawdust]

I have a substantial CSV to import but can't seem to import even the simplest CSV.

I'm running the latest stable REvolution R on OS X if that is pertinent.

Here's the contents of a simple test2.csv CSV file:

#,Status,Project  
5842,New,Test

> snortalerts = read.table( "/Users/lcox/Documents/test2.csv", header=TRUE, sep=",", row.names="#")
Error in data[[rowvar]] : attempt to select less than one element

I can't see how it could get any more simple, yet it doesn't work.  I'm obviously missing something basic, but based on the error, I can't see what it is.   Any quick help or tips on import and common errors for importing data?

Landon

[esawdust]

esawdust wrote

Here's the contents of a simple test2.csv CSV file:

#,Status,Project  
5842,New,Test

> snortalerts = read.table( "/Users/lcox/Documents/test2.csv", header=TRUE, sep=",", row.names="#")
Error in data[[rowvar]] : attempt to select less than one element

Landon

Figured out the answer, though it wasn't obvious (to me anyway).  The symbol "#" used as the first column label was the problem.   I changed that to be "id" and changed the read.table to be:

snortalerts <- read.table( "/Users/lcox/Documents/test2.csv", header=TRUE, sep=",", row.names="id")

and it worked fine.  

[William Dunlap]

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of esawdust
> Sent: Tuesday, September 01, 2009 8:53 AM
> To: [hidden email]
> Subject: [R] Simple question about error on CSV import
>
>
>
> I have a substantial CSV to import but can't seem to import even the
> simplest CSV.
>
> I'm running the latest stable REvolution R on OS X if that is
> pertinent.
>
> Here's the contents of a simple test2.csv CSV file:
>
> #,Status,Project  
> 5842,New,Test
>
> > snortalerts = read.table(
> "/Users/lcox/Documents/test2.csv", header=TRUE,
> > sep=",", row.names="#")
> Error in data[[rowvar]] : attempt to select less than one element
>
> I can't see how it could get any more simple, yet it doesn't
> work.  I'm
> obviously missing something basic, but based on the error, I
> can't see what
> it is.

Using '#' for the initial column name presents 2 problems:
   (a) # is the default comment character so that line is
       ignored.  Add the read.table argument comment.char=""
       to take care of that.
   (b) It looks like the column names are converted to legal
       R names before the row.names="name" is processed
       and the "#" is not legal so it becomes something random
       like "X.".  If you turn off this conversion to legal names
       with check.names=FALSE then things will work.  It
       might be better to use the index of the row.names column
       instead of the name, as in row.names=1.

E.g.,

> t<-"#,Status,Project\n5842,New,Test\n"
> read.table(textConnection(t), header=TRUE, sep=",", comment.char="",
check.names=FALSE, row.names="#")
     Status Project
5842    New    Test
> read.table(textConnection(t), header=TRUE, sep=",", comment.char="",
row.names=1)
     Status Project
5842    New    Test

Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com
 

> Landon
> --
> View this message in context:
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> t-tp25242899p25242899.html
> Sent from the R help mailing list archive at Nabble.com.
>
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>

______________________________________________
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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.

[lwaldron]

 By default for read.table,

comment.char = "#"

so the first line was being treated as a comment line, and when you
specified row.names="#", read.table couldn't find that column.

On Tue, Sep 1, 2009 at 12:07 PM, esawdust <[hidden email]> wrote:

>
>
> esawdust wrote:
> >
> > Here's the contents of a simple test2.csv CSV file:
> >
> > #,Status,Project
> > 5842,New,Test
> >
> >> snortalerts = read.table( "/Users/lcox/Documents/test2.csv",
> header=TRUE,
> >> sep=",", row.names="#")
> > Error in data[[rowvar]] : attempt to select less than one element
> >
> > Landon
> >
>
> Figured out the answer, though it wasn't obvious (to me anyway).  The
> symbol
> "#" used as the first column label was the problem.   I changed that to be
> "id" and changed the read.table to be:
>
> snortalerts <- read.table( "/Users/lcox/Documents/test2.csv", header=TRUE,
> sep=",", row.names="id")
>
> and it worked fine.
> --
> View this message in context:
> http://www.nabble.com/Simple-question-about-error-on-CSV-import-tp25242899p25243159.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.
>

--
Levi Waldron
post-doctoral fellow
Jurisica Lab, Ontario Cancer Institute
Division of Signaling Biology
TMDT 9-304D
101 College Street
Toronto, Ontario M5G 1L7
[phone]

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[esawdust]

thank you all for the quick responses and helpful explanations.  I'm just getting started with R, so I'll get tripped up by some of this until I get in the groove.

Thanks again,

Landon