[R] Strange behaviour of sapply function.

[bickis m@iii@g oii m@th@us@sk@c@]

Thanks.    You are right.  I have realized that the atv function returns
empty for negative arguments.  I was not aware that this would affect how
sapply processes its result.

>
> Quoting bickis using math.usask.ca:
>
>> Here is are a few lines of my R session:
>>
>>> class(income)
>> [1] "integer"
>>> class(sapply(1000*income-999,atv,sktaxb,sktax))
>> [1] "numeric"
>>> class(sapply(1000*income-1001,atv,sktaxb,sktax))
>> [1] "list"
>>
>> Although "income" is a numeric array, and sapply works as expected
>> returning an array (the function "atv" returns a single numeric
>> argument),
>> if subtract a large enough number from the first argument, the sapply
>> function now wants to return a list?   Am I missing something?
>>
>> I am running version 3.3.2 on Mac OS 10.9.9
>>
>
> You have not shown what 'income', 'atv', and so on are; so there is an
> infinity
> of possible reasons why you get a list instead of a numeric vector.
>
> One possible reason: what if 'atv' sometimes returns no value at all?
>
> f <- function(x) x[x>0]
> str(sapply(1:10, f))
> ## int [1:10] 1 2 3 4 5 6 7 8 9 10
>
> str(sapply(-5:5, f))
> ## List of 11
> ##  $ : int(0)
> ##  $ : int(0)
> ##  $ : int(0)
> ##  $ : int(0)
> ##  $ : int(0)
> ##  $ : int(0)
> ##  $ : int 1
> ##  $ : int 2
> ##  $ : int 3
> ##  $ : int 4
> ##  $ : int 5
>
> --
> Enrico Schumann
> Lucerne, Switzerland
> http://enricoschumann.net
>
>