R help - Aug 2010 - how to eliminate an element of a list

Hi,

I want to eliminate an element of a list:

list <- seq(1,5,1)
s <- sample(list,1)

lets say s=3
Now I want to remove 3 from the list: list2 = {1,2,4,5}

Can someone give me a tip?

Thanks,
André

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Try this:

setdiff(list, s)

On Thu, Aug 12, 2010 at 5:32 PM, André de Boer <rnieuws@gmail.com> wrote:
> Hi,
>
> I want to eliminate an element of a list:
>
> list <- seq(1,5,1)
> s <- sample(list,1)
>
> lets say s=3
> Now I want to remove 3 from the list: list2 = {1,2,4,5}
>
> Can someone give me a tip?
>
> Thanks,
> André
>
>        [[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.
>
>

-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

	[[alternative HTML version deleted]]

Hello Andr?,
> I want to eliminate an element of a list:
>
> list <- seq(1,5,1)
That's not a list, it's a vector
> s <- sample(list,1)
>
> lets say s=3
> Now I want to remove 3 from the list: list2 = {1,2,4,5}
If all values are unique as in your example, this will work
x <- 1:5
s <- sample(x, 1)
x <- x[ x != s ]

The last step could also be...
x <- x[ -match(s, x) ]  # note minus sign

Lots of other was to do it too.

Note, I'm assuming you won't always have values equal to the element
indices.

Michael

Try to do this
> list <- seq(1,5,1) 
> list<-list[-3]
> list
[1] 1 2 4 5

list[-x] will remove the xth value in your list. Also you can do something
like
> list[-c(1:4)]
[1] 5
To remove values at indexes 1-4
> list[-c(1,4)]
[1] 2 3 5
To remove values at indexes 1 and 4
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> list<-seq(2,10,2)
> list
[1]  2  4  6  8 10
> list[-which(2==list)]
[1]  4  6  8 10

using the which() will let you remove things from a list that have a
specified value... I usually use the 

blah<- blah[-which(TRUE==is.na(blah)) ]

which will remove all NA values in your list
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On Aug 13, 2010, at 4:06 PM, fishkbob wrote:
>
>> list<-seq(2,10,2)
>> list
> [1]  2  4  6  8 10
>> list[-which(2==list)]
> [1]  4  6  8 10
>
> using the which() will let you remove things from a list that have a
> specified value... I usually use the
>
> blah<- blah[-which(TRUE==is.na(blah)) ]
>
> which will remove all NA values in your list
Although which() is useful when used with "[" because it avoids the NA
indexing problem,  it is entirely superfluous here.

  blah<- blah[-is.na(blah) ]   # will be more efficient
>
-- 

David Winsemius, MD
West Hartford, CT