Thanks Jeff et. all,
This is exactly what I needed.
-----Original Message-----
From: "Jeff Newmiller" [jdnew...@dcn.davis.ca.us]
Date: 07/12/2014 10:38 AM
To: "Uwe Ligges" <lig...@statistik.tu-dortmund.de>, "ce" <zadi...@excite.com>,
r-help@r-project.org
Subject: Re: [R] lapply returns NULL ?
I think that removing them is something the OP doesn't understand how to do.
The lapply function ALWAYS produces an output element for every input element.
If this is not what you want then you need to choose a looping structure that
is not so tightly linked to the input, such as a for loop (untested):
result <- list()
for (nm in names(foo)) {
if ( 1 == foo[[nm]][1] ) {
result[[ nm ]] <- foo[[ nm ]]
}
}
result
or use vector indexing (lists are a special kind of vector) with the loop
result:
foo[ sapply(foo,function(v){1==v[1]}) ]
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Sent from my phone. Please excuse my brevity.
On July 12, 2014 6:37:44 AM PDT, Uwe Ligges <lig...@statistik.tu-dortmund.de>
wrote:
>
>
>On 12.07.2014 15:25, ce wrote:
>>
>>
>> Dear all,
>>
>> I have a list of arrays :
>>
>> foo<-list(A = c(1,3), B =c(1, 2), C = c(3, 1))
>>
>>> foo
>> $A
>> [1] 1 3
>>
>> $B
>> [1] 1 2
>>
>> $C
>> [1] 3 1
>>
>>> if( foo$C[1] == 1 ) foo$C[1]
>>
>>> lapply(foo, function(x) if(x[1] == 1 ) x )
>>
>> $A
>> [1] 1 3
>>
>> $B
>> [1] 1 2
>>
>> $C
>> NULL
>>
>> I don't want to list $C NULL in the output. How I can do that ?
>
>Either use your own print function or, if you do not want NULL elements
>
>in the object, remove them.
>
>Best,
>Uwe Ligges
>
>
>> ______________________________________________
>> 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.
>>
>
>______________________________________________
>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.
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and provide commented, minimal, self-contained, reproducible code.
