Folks,

Updating values in a table is simple in SAS or SQL, but I've wracked my 
brain looking for an elegant solution in R to no avail thus far. Certainly 
this is a common need that's been solved in dozens of different ways.

Given an initial dataframe nn and a smaller dataframe of updates uu, I'd 
like to replace the values in 
nn <- expand.grid('a'=1:4, 'b'=1:3)
nn$x <- runif(nrow(nn))
nn$y <- runif(nrow(nn))
uu <- rbind(data.frame('a'=1, 'b'=1, 'x'=100, 'y'=-100)
           ,data.frame('a'=2, 'b'=2, 'x'=200, 'y'=-100)
           ,data.frame('a'=4, 'b'=1, 'x'=400, 'y'=-100)
           ,data.frame('a'=3, 'b'=3, 'x'=300, 'y'=-100)
           )

I'd like the result <- f(nn, uu) to look like
   a b         x         y
1  1 1 100       -100
2  2 1 0.8310890 0.2516533
3  3 1 0.4304501 0.3004313
4  4 1 400       -100
5  1 2 0.9546661 0.2935739
6  2 2 200       -100
7  3 2 0.6941463 0.9356967
8  4 2 0.9642832 0.9253482
9  1 3 0.8735154 0.6055080
10 2 3 0.6665369 0.2938112
11 3 3 300       -100
12 4 3 0.7268327 0.4536969

Anyone spare a clue about what f() might look like?
Thanks,
cur

-- 
Curt Seeliger, Data Ranger
Raytheon Information Services - Contractor to ORD
seeliger.curt@epa.gov
541/754-4638

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