[R] Bug or feature with finding a list element?

Chunhao Tu tu_chunhao at yahoo.com
Thu Oct 2 06:39:20 CEST 2008


Hi,
I have tried this with R-2.7.2 then I got
> alist[['goodbye']] 
NULL
> alist[['hi']] 
NULL
> alist[['hello']] 
[1] 10
The results make sense to me thus you might want to update your R version.

chunhao


B Fox wrote:
> 
> This seems odd.  When I try to look up a list element which has a space in
> the name using just the first word (i.e. no spaces), it will sometimes
> return the element with a space in the name and sometimes it will return
> NULL.
> 
> Try this:
> 
> alist <- list( 'hello'=10, bye=20, 'hello world'=30, 'goodbye world'=40,
> 'hi
> world'=50, 'goodbye foo'=60, 'goodbye bar'=70)
> Then try fetching some list elements:
>> alist[['goodbye']]
> NULL
>> alist[['hi']]
> [1] 50
>> alist[['hello']]
> [1] 10
> With "goodbye" there were a couple list elements with spaces in the name,
> so
> it didn't return any of them.
> 
> With "hi" there was one (and only one) element which had "hi" as the first
> word: "hi world"
> 
> With "hello" there was an actual element named "hello"
> 
> This seems messed up and non-intuitive to say the least.
> 
> I am doing this on R version 2.5.0 (2007-04-23) compiled on a itanium64
> and I also tried it on R version 2.5.1 (2007-06-27) on an pentium 4 ubuntu
> linux
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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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.
> 
> 

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