You can join data from ore.frame objects that represent database tables by using the merge function, as shown in Example 3-5. The example creates two data.frame objects and merges them. It then invokes the ore.create function to create a database table for each data.frame object. The ore.create function automatically generates an ore.frame object as a proxy object for the table. The ore.frame object has the same name as the table. The example merges the ore.frame objects. Note that the order of the results of the two merge operations is not the same because the ore.frame objects are unordered.
Example 3-5 Joining Data from Two Tables
# Create data.frame objects. df1 <- data.frame(x1=1:5, y1=letters[1:5]) df2 <- data.frame(x2=5:1, y2=letters[11:15]) # Combine the data.frame objects. merge (df1, df2, by.x="x1", by.y="x2") # Create database tables and ore.frame proxy objects to correspond to # the local R objects df1 and df2. ore.create(df1, table="DF1_TABLE") ore.create(df2, table="DF2_TABLE") # Combine the ore.frame objects. merge (DF1_TABLE, DF2_TABLE, by.x="x1", by.y="x2")Listing for Example 3-5
R> # Create data.frame objects. R> df1 <- data.frame(x1=1:5, y1=letters[1:5]) R> df2 <- data.frame(x2=5:1, y2=letters[11:15]) R> # Combine the data.frame objects. R> merge (df1, df2, by.x="x1", by.y="x2") x1 y1 y2 1 1 a o 2 2 b n 3 3 c m 4 4 d l 5 5 e k R> # Create database tables and ore.frame proxy objects to correspond to R> # the local R objects df1 and df2. R> ore.create(df1, table="DF1_TABLE") R> ore.create(df2, table="DF2_TABLE") R> # Combine the ore.frame objects. R> merge (DF1_TABLE, DF2_TABLE, by.x="x1", by.y="x2") x1 y1 y2 1 5 e k 2 4 d l 3 3 c m 4 2 b n 5 1 a o Warning message: ORE object has no unique key - using random order