[R] Frequencies for a list of vectors

[William Dunlap]

Using vapply instead of sapply or unlist(lapply) here gives you a
little more safety.  vapply insists that you supply a FUN.VALUE
argument that gives a prototype (type and length) of the expected
output of FUN.  It will stop if FUN returns something unexpected.
Compare the following where I misspelled 'collapse'; only vapply
catches the error:

> marieData <- list('30008'=c(1,0,1,0), '60008'=c(0,0,1,0), '90008'=c(0,0,1,0), '100007'=1, '130001'=c(0,1))
> unlist(lapply(marieData, paste, collaps=''))
 300081  300082  300083  300084  600081  600082  600083  600084  900081  900082
   "1 "    "0 "    "1 "    "0 "    "0 "    "0 "    "1 "    "0 "    "0 "    "0 "
 900083  900084  100007 1300011 1300012
   "1 "    "0 "    "1 "    "0 "    "1 "
> sapply(marieData, paste, collaps='')
$`30008`
[1] "1 " "0 " "1 " "0 "

$`60008`
[1] "0 " "0 " "1 " "0 "

$`90008`
[1] "0 " "0 " "1 " "0 "

$`100007`
[1] "1 "

$`130001`
[1] "0 " "1 "

> vapply(marieData, paste, collaps='', FUN.VALUE='')
Error in vapply(marieData, paste, collaps = "", FUN.VALUE = "") :
  values must be length 1,
 but FUN(X[[1]]) result is length 4

vapply(X,FUN,FUN.VALUE) also gives you a better result when length(X)
is 0, meaning that you don't have to write special code to catch that
case.


Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Tue, Aug 5, 2014 at 1:53 PM, Peter Alspach
<Peter.Alspach at plantandfood.co.nz> wrote:
> Alternatively, use sapply instead of lapply ....
>
> marieData <- list('30008'=c(1,0,1,0), '60008'=c(0,0,1,0), '90008'=c(0,0,1,0), '100007'=1, '130001'=c(0,1))
> marieData
> $`30008`
> [1] 1 0 1 0
>
> $`60008`
> [1] 0 0 1 0
>
> $`90008`
> [1] 0 0 1 0
>
> $`100007`
> [1] 1
>
> $`130001`
> [1] 0 1
>
> table(sapply(marieData, paste, collapse=''))
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Rui Barradas
> Sent: Wednesday, 6 August 2014 8:49 a.m.
> To: Marie-Pierre Sylvestre; r-help at r-project.org
> Subject: Re: [R] Frequencies for a list of vectors
>
> Hello,
>
> Maybe something like
>
> table(unlist(lapply(HTNlist, paste, collapse = '')))
>
>
> (Untested, it's a bad idea not to use ?dput to give a data example.) Use
>
> dput(head(HTNlist))  # paste the output of this in a mail
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> Em 05-08-2014 18:39, Marie-Pierre Sylvestre escreveu:
>> Dear R users,
>>
>> I have a list of vectors (list is called HTNlist). Each vector is of
>> length
>> 1 to 4 and takes only 0 and 1 as values. E.g.
>>
>> head(HTNlist)
>> $`30008`
>> [1] 1 0 1 0
>>
>> $`60008`
>> [1] 0 0 1 0
>>
>> $`90008`
>> [1] 0 0 1 0
>>
>> $`100007`
>> [1] 1
>>
>> $`130001`
>> [1] 0 1
>>
>> $`130007`
>> [1] 1 0 1 0
>>
>> I would like to obtain a frequency table for the elements of the list.
>> I want to know how many of
>> '1 0 0' I have in the list, how many '1 0 1 0' etc.
>>
>> Can you please help?
>>
>> Thank you in advance,
>> MP
>>
>>       [[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.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
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> and provide commented, minimal, self-contained, reproducible code.
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>
> ______________________________________________
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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.