R help - Aug 2009 - a naive question

Hi, and my apologies for the following very naive question : I would like to
read a column of numbers in R and plot a histogram.

eg :

x<-read.table("txSTART");
y<-as.numeric(x);

and I do obtain the error : Error: (list) object cannot be coerced to type
'double'. Please could you let me know the way to fix it.

thanks,

bogdan
<r-help@r-project.org>

	[[alternative HTML version deleted]]

Hi,

On Aug 19, 2009, at 4:59 PM, Bogdan Tanasa wrote:
> Hi, and my apologies for the following very naive question : I would  
> like to
> read a column of numbers in R and plot a histogram.
>
> eg :
>
> x<-read.table("txSTART");
> y<-as.numeric(x);
>
> and I do obtain the error : Error: (list) object cannot be coerced  
> to type
> 'double'. Please could you let me know the way to fix it.
Yeah, you can't do that. What does x look like? Can you show us the  
result of:

R> head(x)

Assuming it's just a single column, you can access the numbers in the  
first column, like so

R> x[,1]

You can use that to plot a histogram of the numbers in the first column:

R> plot(hist(x[,1]))

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
   |  Memorial Sloan-Kettering Cancer Center
   |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact

read.table produces a data.frame (a special list) even when you have only
one column.
Try y<-as.numeric(x[[1]])

On Wed, Aug 19, 2009 at 3:59 PM, Bogdan Tanasa <tanasa@gmail.com> wrote:
> Hi, and my apologies for the following very naive question : I would like
> to
> read a column of numbers in R and plot a histogram.
>
> eg :
>
> x<-read.table("txSTART");
> y<-as.numeric(x);
>
> and I do obtain the error : Error: (list) object cannot be coerced to type
> 'double'. Please could you let me know the way to fix it.
>
> thanks,
>
> bogdan
> <r-help@r-project.org>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@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.
>


-- 
Jun Shen PhD
PK/PD Scientist
BioPharma Services
Millipore Corporation
15 Research Park Dr.
St Charles, MO 63304
Direct: 636-720-1589

	[[alternative HTML version deleted]]

Bogdan:

I believe your query demonstrates the hazards of jumping into R without
first making an effort to read at least some of the supporting docs -- in
this case, I think, "An Intro to R" would have sufficed.

R is not a video game nor even Excel. It is very powerful and quite
sophisticated software for doing some pretty hairy stuff, implemented in its
"raw" form as an interactive programming language (apologies if this
is not
the appropriate technical term). So, as I think you found out, it can make
some pretty daunting demands on a beginner even for simple things. If you
really need it's power and flexibility, once you've climbed the learning
curve, it's an extraordinarily productive tool. If you are just a casual
reader who doesn't need all that complex functionality, it's probably
not
worth the effort or frustration.

Anyway, the answer to your question -- which may require you to read the
docs to understand -- is that in R a "table" from read.table() is
actually a
data frame, which is also a special kind of list. As the error message says,
as.numeric() cannot coerce recursive objects (which is what a list is) to
simple numeric vectors. 

Bert Gunter
Genentech Nonclinical Biostatisics

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of Bogdan Tanasa
Sent: Wednesday, August 19, 2009 1:59 PM
To: r-help at r-project.org
Subject: [R] a naive question

Hi, and my apologies for the following very naive question : I would like to
read a column of numbers in R and plot a histogram.

eg :

x<-read.table("txSTART");
y<-as.numeric(x);

and I do obtain the error : Error: (list) object cannot be coerced to type
'double'. Please could you let me know the way to fix it.

thanks,

bogdan
<r-help at r-project.org>

	[[alternative HTML version deleted]]

______________________________________________
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.