[R] Behavior of seq with vector from

Rowe, Brian Lee Yung (Portfolio Analytics) B_Rowe at ml.com
Fri May 22 17:01:33 CEST 2009

So if I want to concatenate the output of multiple seq calls, there's no clear way to to do this?

For background, I have a number of data.frames with the same structure in a list. I want to 'collapse' the list into a single data.frame but only keeping certain columns from each underlying data.frame. In my example below, I want to keep columns 2,3 in each underlying data.frame.

I'm using do.call('cbind', my.list) and then using the statement below to extract only the columns I need (other details omitted for brevity). If there's a built-in or pre-built function to do this, I'm all eyes.


PS if this is unclear, flame away, and I'll post some code

-----Original Message-----
From: Peter Dalgaard [mailto:P.Dalgaard at biostat.ku.dk] 
Sent: Friday, May 22, 2009 6:20 AM
To: Rowe, Brian Lee Yung (Portfolio Analytics)
Cc: r-help at r-project.org
Subject: Re: [R] Behavior of seq with vector from

Rowe, Brian Lee Yung (Portfolio Analytics) wrote:
> To get the value I want, I am using the following code:
>> sort(as.vector(apply(array(c(2,3)), 1, seq, by=3,length.out=4)))
> [1]  2  3  5  6  8  9 11 12
> So two questions:
> 1. Is seq designed/intended to be used with a vector from argument, and
> is this the desired behavior?
> 2. If so, is there a cleaner way of implementing what I want?

1. Hmm, not really. NA.

2. I'd view it as an outer sum, stringed out to a single vector, hence:

> c(outer(c(2,3), seq(0,,3,4), "+"))
[1]  2  3  5  6  8  9 11 12

   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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 (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
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