[R] variable length lisin in data frame

[William Dunlap]

> d <- data.frame(id=1:4,  no.contacts=c(2,3,3,1))
> d$contacts_list <- list(3:4, c(1,3,4), c(4,2,1), 1 )

If you store that information in a longer format, with each row being
an edge to the relationship graph, it can make further processing
easier:

  d2 <- with(d,
    data.frame(id=rep(id, vapply(contacts_list,length,0)),
contacts_list=unlist(contacts_list)))

At that point you may want to install and load the igraph package,
convert d2 to an 'igraph' object, and use use package:igraph's
functions on it:
  install.packages("igraph")
  library(igraph)
  g <- graph.data.frame(d2)
  neighbors(g, 2, mode="out")
  # [1] 1 3 4
  neighbors(g, 2, mode="in")
  # [1] 3
  plot(g)

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Sat, May 10, 2014 at 5:20 AM, Duncan Murdoch
<murdoch.duncan at gmail.com> wrote:
> On 10/05/2014, 7:46 AM, Ragia Ibrahim wrote:
>>
>> Dear Group,
>> I have data like the following
>>
>> id   contacts_list   number of contacts
>> ---------------------------------------------------
>> 1   3 4                               2
>> 2   1 3 4                            3
>> 3    4 2 1                           3
>> 4    1                                1
>> ------------------------------------------------------
>>
>>
>> can you kindly please sugest a data type in R to use for it?
>> i thought about data frame that consists of a  list element. but  lists
>> are not in  the same length, any  solutions?
>
>
> You can use a dataframe, but the data.frame function gets confused by the
> contacts_list, so you need to set it up in two steps, e.g.
>
> d <- data.frame(id=1:4,  no.contacts=c(2,3,3,1))
> d$contacts_list <- list(3:4, c(1,3,4), c(4,2,1), 1 )
>
> Other dataframe functions (e.g. printing, indexing, etc.) should work:
>
>> d
>   id no.contacts contacts_list
> 1  1           2          3, 4
> 2  2           3       1, 3, 4
> 3  3           3       4, 2, 1
> 4  4           1             1
>
>> d[2,]
>   id no.contacts contacts_list
> 2  2           3       1, 3, 4
>
> A slightly confusing bit is that if you pick out a single element of column
> 3 you'll get a list containing it:
>
>> d[2,3]
> [[1]]
> [1] 1 3 4
>
> so you should use the double bracket list-indexing style:
>
>> d[[2,3]]
> [1] 1 3 4
>
> Duncan Murdoch
>
>
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