[R] Generate a vector of values, given a vector of keys and a table?

[peter dalgaard]

Or change the data format slightly and use indexing:

> l
     key    val    
[1,] "1.1"  "10000"
[2,] "1.9"  "10000"
[3,] "1.4"  "15000"
[4,] "1.5"  "20000"
[5,] "1.15" "25000"
> v <- l[,2]
> names(v) <- l[,1]
> x <- c("1.9", "1.9", "1.1", "1.1", "1.4", "1.4", "1.5", "1.5", "1.5", 
+ "1.5")
> v[x]
    1.9     1.9     1.1     1.1     1.4     1.4     1.5     1.5     1.5     1.5 
"10000" "10000" "10000" "10000" "15000" "15000" "20000" "20000" "20000" "20000" 
> 


On 11 Sep 2015, at 07:30 , Bert Gunter <bgunter.4567 at gmail.com> wrote:

> ?match
> 
> as in:
> 
>> y <- lk_up[match(x,lk_up[,"key"]),"val"]
>> y
> [1] "10000" "10000" "10000" "10000" "15000" "15000" "20000"
> [8] "20000" "20000" "20000"
> 
> 
> 
> Bert
> 
> 
> 
> Bert Gunter
> 
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
>   -- Clifford Stoll
> 
> 
> On Thu, Sep 10, 2015 at 10:04 PM, David Wolfskill <r at catwhisker.org> wrote:
>> I apologize in advance: I must be overlooking something quite simple,
>> but I'm failing to make progress.
>> 
>> Suppose I have a "lookup table":
>> 
>> Browse[2]> dput(lk_up)
>> structure(c("1.1", "1.9", "1.4", "1.5", "1.15", "10000", "10000",
>> "15000", "20000", "25000"), .Dim = c(5L, 2L), .Dimnames = list(
>>    NULL, c("key", "val")))
>> Browse[2]> lk_up
>>     key    val
>> [1,] "1.1"  "10000"
>> [2,] "1.9"  "10000"
>> [3,] "1.4"  "15000"
>> [4,] "1.5"  "20000"
>> [5,] "1.15" "25000"
>> 
>> and a vector whose elements correspond with the "key" column of the
>> table:
>> 
>> Browse[2]> dput(x)
>> c("1.9", "1.9", "1.1", "1.1", "1.4", "1.4", "1.5", "1.5", "1.5",
>> "1.5")
>> Browse[2]> x
>> [1] "1.9" "1.9" "1.1" "1.1" "1.4" "1.4" "1.5" "1.5" "1.5" "1.5"
>> Browse[2]>
>> 
>> Is there a (relatively) simple (i.e., not explicitly looping) construct
>> that will yield a vector of the same size and shape as "x", but contain
>> the "value" entries from the lookup table (preserving the sequence: the
>> 1st entry of the result must correspond to the 1st entry of the list of
>> keys) -- in the current example:
>> 
>> Browse[2]> dput(y)
>> c("10000", "10000", "10000", "10000", "15000", "15000", "20000",
>> "20000", "20000", "20000")
>> Browse[2]> y
>> [1] "10000" "10000" "10000" "10000" "15000" "15000" "20000" "20000"
>> "20000" "20000"
>> Browse[2]>
>> 
>> I am (unfortunately) presently limited to R-3.0.2.
>> 
>> Thanks....
>> 
>> Peace,
>> david
>> --
>> David H. Wolfskill                              r at catwhisker.org
>> Those who would murder in the name of God or prophet are blasphemous cowards.
>> 
>> See http://www.catwhisker.org/~david/publickey.gpg for my public key.
>> 
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com