Example 2-16 Ordering Using Row Names

# Prepare the data.
library(kernlab)
data(spam)
s <- spam
# Create a column that has integer values.
s$TS <- 1001:(1000 + nrow(s))
# Create a column that has integer values with each number repeated twice.
s$USERID <- rep(351:400, each=2, len=nrow(s))
# Ensure that the database tables do not exist.
ore.drop(table='SPAM_PK')
ore.drop(table='SPAM_NOPK')
# Create database tables.
ore.create(s[,c(59:60,1:28)], table="SPAM_PK")
ore.create(s[,c(59:60,1:28)], table="SPAM_NOPK")
# Using a SQL statement, alter the SPAM_PK table to add a composite primary key.
ore.exec("alter table SPAM_PK add constraint SPAM_PK primary key
           (\"USERID\",\"TS\")")
# Synchronize the table to get the change to it.
ore.sync(table = "SPAM_PK")
# 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])

R> # Prepare the data.
R> library(kernlab)
R> data(spam)
R> s <- spam
R> # Create a column that has integer values.
R> s$TS <- 1001:(1000 + nrow(s))
R> # Create a column that has integer values with each number repeated twice.
R> s$USERID <- rep(351:400, each=2, len=nrow(s))
R> # Ensure that the database tables do not exist.
R> ore.drop(table='SPAM_PK')
R> ore.drop(table='SPAM_NOPK')
R> # Create database tables.
R> ore.create(s[,c(59:60,1:28)], table="SPAM_PK")
R> ore.create(s[,c(59:60,1:28)], table="SPAM_NOPK")
R> # Using a SQL statement, alter the SPAM_PK table to add a composite primary key.
R> ore.exec("alter table SPAM_PK add constraint SPAM_PK primary key
+  (\"USERID\",\"TS\")")
R> # Synchronize the table to get the change to it.
R> ore.sync(table = "SPAM_PK")
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