You can use row names to order an ore.frame object, as demonstrated in Example 2-14. The example creates a data.frame object in the local R session memory and pushes it to the ore.frame object with the symbol a, which exists in the memory of the Oracle database to which the R session is connected. The example shows that the ore.frame object has the default row names of the R data.frame object. Because the ore.frame object is ordered, invoking the row.names function on it does not produce a warning message.
The example uses the ordered SPAM_PK and unordered SPAM_NOPK ore.frame objects from Example 2-13 to show that invoking row.names on the unordered SPAM_NOPK produces a warning message but invoking it on the ordered SPAM_PK does not.
The SPAM_PK object is ordered by the row names, which are the combined values of the TS and USERID column values separated by the "|" character. The example shows that you can change the row names.
Example 2-14 Ordering Using Row Names
# Create an ordered ore.frame by default. a <- ore.push(data.frame(a=c(1:10,10:1), b=letters[c(1:10,10:1)])) # Display the values in the b column. Note that because the ore.frame is # ordered, no warnings appear. a$b # Display the default row names for the first six rows of the a column. row.names(head(a)) # SPAM_NOPK has no unique key, so row.names raises error messages. row.names(head(SPAM_NOPK)) # Row names consist of TS ‘|' USERID. # For display on this page, only the first four row names are shown. row.names(head(SPAM_PK)) # Reassign the row names to the TS column only row.names(SPAM_PK) <- SPAM_PK$TS # The row names now correspond to the TS values only. row.names(head(SPAM_PK[,1:4])) head(SPAM_PK[,1:4])Listing for Example 2-14
R> # Create an ordered ore.frame by default.
R> a <- ore.push(data.frame(a=c(1:10,10:1), b=letters[c(1:10,10:1)]))
R> # Display the values in the b column. Note that because the ore.frame is
R> # ordered, no warnings appear.
R> a$b
[1] a b c d e f g h i j j i h g f e d c b aLevels: a b c d e f g h i j
R> # Display the default row names for the first six rows of the a column.
R> row.names(head(a))
[1] 1 2 3 4 5 6
R> # SPAM_NOPK has no unique key, so row.names raises error messages.
R> row.names(head(SPAM_NOPK))
Error: ORE object has no unique key
In addition: Warning message:
ORE object has no unique key - using random order
R> # Row names consist of TS ‘|' USERID.
R> # For display on this page, only the first four row names are shown.
R> row.names(head(SPAM_PK))
1001|351 1002|351 1003|352 1004|352
"1001|3.51E+002" "1002|3.51E+002" "1003|3.52E+002" "1004|3.52E+002"
R> # Reassign the row names to the TS column only
R> row.names(SPAM_PK) <- SPAM_PK$TS
R> # The row names now correspond to the TS values only.
R> row.names(head(SPAM_PK[,1:4]))
[1] 1001 1002 1003 1004 1005 1006
R> head(SPAM_PK[,1:4])
TS USERID make address
1001 1001 351 0.00 0.64
1002 1002 351 0.21 0.28
1003 1003 352 0.06 0.00
1004 1004 352 0.00 0.00
1005 1005 353 0.00 0.00
1006 1006 353 0.00 0.00