Perhaps using the R merge() function, possibly twice in succession,
will do the job. (merge() does a one to many relational join, but
with only two dataframes at at time).
Or, there is an R package that lets you use the SQL language on
dataframes. I don't recall its name, but a search on R packages
should turn it up -- if someone else doesn't provide the name sooner.
-Don
At 10:52 AM -0800 1/22/10, GL wrote:
I need to merge three datasets and don't know how. If I were using SQL, I
would use df3, look up the characteristics of each date in df1 and the value
for each observation in df2.
df1 - unique list of Dates and characteristics of those dates
Date, YYYYMM, YYYYWW, DOW
df2 - the raw data
Date, Place, Value
df3 - all posibile combinations of Date + Place (via
expand.grid(unique(df2$Date),unique(df2$Place))
Date, Place
I need to end up with:
Date, YYYYMM, YYYYWW, DOW, PLace, Value (plug 0 if combo doesn't exist in
raw data).
Appreciate any help!
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--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
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