R help - May 2010 - accessing a data frame with row names

Readers,

I have entered a file into r:

,column1,column2
row1,0.1,0.2
row2,0.3,0.4

using the command:

dataframe<-read.table("/path/to/file.csv",header=T,row.names=1)

When I try the command:

dataframe[,2]

I receive the response:

NULL

I was expecting:

row1 0.2
row2 0.4

What is my error with the syntax please?

Yours,

r251
mandriva2009

Use read.csv or read.table(..., sep = ",").  Also note that if you
delete the first comma of the header (as in the second example below)
you won't have to specify row.names since it can figure it out from
the fact that there is one fewer column name than data fields.
> Lines <- ",column1,column2
+ row1,0.1,0.2
+ row2,0.3,0.4"
>
> read.csv(textConnection(Lines), row.names = 1)
     column1 column2
row1     0.1     0.2
row2     0.3     0.4
>
>
> Lines2 <- "column1,column2
+ row1,0.1,0.2
+ row2,0.3,0.4"
>
> read.csv(textConnection(Lines2))
     column1 column2
row1     0.1     0.2
row2     0.3     0.4


On Mon, May 31, 2010 at 7:23 AM, e-letter <inpost at gmail.com>
wrote:
> Readers,
>
> I have entered a file into r:
>
> ,column1,column2
> row1,0.1,0.2
> row2,0.3,0.4
>
> using the command:
>
>
dataframe<-read.table("/path/to/file.csv",header=T,row.names=1)
>
> When I try the command:
>
> dataframe[,2]
>
> I receive the response:
>
> NULL
>
> I was expecting:
>
> row1 0.2
> row2 0.4
>
> What is my error with the syntax please?
>
> Yours,
>
> r251
> mandriva2009
>
> ______________________________________________
> 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.
>

Hi,

Let's create your data.frame:
 > dataframe <- structure(list(column1 = c(0.1, 0.3), column2 = c(0.2, 
0.4)), .Names = c("column1",
"column2"), row.names = c("row1", "row2"), class =
"data.frame")
 > dataframe[,2]
[1] 0.2 0.4
 > dataframe[,2, drop=FALSE]
      column2
row1     0.2
row2     0.4

So I don't know what's wrong with your data.
Maybe, providing the output from str(dataframe) would help us to help you!

HTH,
Ivan

Le 5/31/2010 13:23, e-letter a ?crit :
> Readers,
>
> I have entered a file into r:
>
> ,column1,column2
> row1,0.1,0.2
> row2,0.3,0.4
>
> using the command:
>
>
dataframe<-read.table("/path/to/file.csv",header=T,row.names=1)
>
> When I try the command:
>
> dataframe[,2]
>
> I receive the response:
>
> NULL
>
> I was expecting:
>
> row1 0.2
> row2 0.4
>
> What is my error with the syntax please?
>
> Yours,
>
> r251
> mandriva2009
>
> ______________________________________________
> 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.
>
>    
-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. S?ugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

**********
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