[R] arrays of arrays

Duncan Murdoch murdoch.duncan at gmail.com
Wed Nov 10 12:40:27 CET 2010


On 10/11/2010 12:12 AM, Michael Bedward wrote:
> Hello Sachin,
>
> You have a "ragged array" and you can easily store this as a list of vectors...
>
> x<- list(c(0,0,1,1), c(1,3,5), 4, c(7, -1, 8, 9, 10, 6))
>
> The only gotcha with this is that you will then need to use double
> brackets for the first index when retrieving values (single brackets
> will return a vector wrapped in a list)...
>
> e.g. x[[2]][3] gives 5

An alternative syntax that is sometimes easier to work with is

x[[c(2,3)]]

This needs the double brackets; x[c(2,3)] would be a list holding items 
2 and 3 from x, i.e. list(c(1,3,5), 4).

Duncan Murdoch

>
> You can query vector length with double brackets...
>
> e.g. length( x[[2]] ) gives 3
>
> Hope this helps,
>
> Michael
>
> On 10 November 2010 16:00,<sachinthaka.abeywardana at allianz.com.au>  wrote:
>> Hi Erik,
>>
>> Thanks for replying. Only problem with that is that each row has 5 elements
>> (or 5 columns). I want varying number of columns as shown in my example.
>>
>> x<-              0               0               1               1
>>                  1               3               5
>>                  4
>>                  7               -1              8               9               10              6
>>
>> Regards,
>> Sachin
>> p.s. sorry about corporate notice.
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