[R] indexing question

[Sundar Dorai-Raj]

Adrian Dusa wrote:

> Hi,
> 
> I have a problem and a rather poor solution that I would like to improve.
> There a 2 datasets with different number of cases like this:
> 
> Dataset 'poploc’                                Dataset 'siruta’
> 
> Case no.     SIRUTA     TYPE                    Case no.     SIRUTA     TYPE
> 1            1017        0                      1            1017        3  
> 2            1026        0                      2            1020        5
> 3            42711       0                      3            1026        4
> ....                                               ....
> 13000        100234      0                      ....
>                                                 16000        160241      3
> 
> I want to bring the TIP variable in the 'poploc’ dataset according to the 
> SIRUTA variable (which has unique codes for each case, in both datasests).
> The resulting dataset 'poploc' should look like this:
> 
> Case no.     SIRUTA     TYPE
> 1            1017        3
> 2            1026        4
> 3            42711       3
> 
> 13000        100234      5
> 
> My current solution involves a combination of FOR looping and indexing, which 
> takes about 3 minutes to complete.
> 
> for (i in 1:nrow(siruta))
> poploc$TIP[poploc$SIRUTA %in% siruta$SIRUTA[i]] <- siruta$TIP[i]
> 
> I’m sure there are more clever solutions, any help appreciated. Thank you!
> Adrian
> 
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I think you are looking for ?merge.

# note that poploc has no `TYPE' column
poploc <- data.frame(no = 1:3, SIRUTA = c(1017, 1026, 42711))
siruta <- data.frame(no = c(1:3, 16000),
                      SIRUTA = c(1017, 1026, 42711, 160241),
                      TYPE = c(3, 5, 4, 3))
merge(poploc, siruta)