[R] Extract row as NA with no matching name

[David Winsemius]

I don't know a clean way of delivering that result but if you use 
logical indexing you can get an empty matrix with three columns:


str( mdat["nope" %in% rownames(mdat), ] )
  num[0 , 1:3]
  - attr(*, "dimnames")=List of 2
   ..$ : NULL
   ..$ : chr [1:3] "C.1" "C.2" "C.3"

# it prints thus to the console

  mdat[FALSE,  ]
#     C.1 C.2 C.3


If you have a vector, test_vec of possible matches you could use:


mdat[ rownames(mdat) %in% test_vec,  ]


**Yet again I am advising you to post in plain text. It's very easy to 
post in plain text from gmail. Please do so.**


-- 

David.

On 8/8/19 8:43 AM, Christofer Bogaso wrote:
> Hi,
>
> Let say I have below matrix
>
> mdat <- matrix(c(1,2,3, 11,12,13), nrow = 2, ncol = 3, byrow = TRUE,
>                 dimnames = list(c("row1", "row2"),
>                                 c("C.1", "C.2", "C.3")))
>
>
> Now I can extract a raw by rowname as
>
>> mdat['row1', ]
> C.1 C.2 C.3
>
>    1   2   3
>
>
> However I am also looking for was to extract values as NA when a
> rowname is supplied which is not existing rownames
>
> I should get
>
>> mdat['new_raw', ]
> C.1 C.2 C.3
>
>    NA   NA   NA
>
>
> Current it throws error as default functionality. Is there any way to
> force R to provide values as NA instead of showing any errore?
>
> 	[[alternative HTML version deleted]]
>
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