[R] (no subject)

[Barry Rowlingson]

lists in R can have multiple elements with the same name but if you
try and access elements by name you only get the first.

For example:

 > a = list(x=99, x=23, x=456)
 > a$x
 [1] 99

Its just the way it is.

Note you might find the `str` function useful to see the structure of R objects:

 > str(Empl)
List of 4
 $ employee: chr "Anna"
 $ family  :List of 3
  ..$ spouse    : chr "Fred"
  ..$ children  : num 3
  ..$ child.ages: num [1:3] 4 7 9
 $ employee: chr "John"
 $ family  :List of 3
  ..$ spouse    : chr "Mary"
  ..$ children  : num 2
  ..$ child.ages: num [1:2] 14 17
 > str(Empl[c(2,4)])
List of 2
 $ family:List of 3
  ..$ spouse    : chr "Fred"
  ..$ children  : num 3
  ..$ child.ages: num [1:3] 4 7 9
 $ family:List of 3
  ..$ spouse    : chr "Mary"
  ..$ children  : num 2
  ..$ child.ages: num [1:2] 14 17
 > str(Empl[c(2,4)]$family)
List of 3
 $ spouse    : chr "Fred"
 $ children  : num 3
 $ child.ages: num [1:3] 4 7 9

With your current data structure you might need to use the
list-processing functions like `sapply` and `lapply` to get out the
spouse names from your list:

 > sapply(Empl[c(2,4)], function(x){x$spouse})
 family family
 "Fred" "Mary"

Keep at it!

On Sun, Oct 4, 2015 at 7:31 PM, FERNANDO MANSITO CABALLERO
<fernando.mansito at gmail.com> wrote:
> Dear Madam/Sir,
>
> I  am   trying to understand  R and I have come to a stumbling block. i
> have written:
>
>>Empl <- list(employee="Anna",family=list(spouse="Fred",children=3,
> +child.ages=c(4,7,9)),employee="John",family=list(spouse="Mary",children=2,
> +child.ages=c(14,17)))
>>Empl[c(2,4)]$family$spouse
> [1] "Fred"
>>#instead of [1] "Fred" "Mary"
>
> Where am I wrong?
>
> Thank you very much for your patience
> Yours truly,
> Fernando Mansito
>
>         [[alternative HTML version deleted]]
>
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