user manual

157
CLEM Language Reference
Special Fields
Special functions are used to denote the specific fields under examination, o r to generate a list
of fields as input. For exampl e, when deriving multiple fields a t once, you should use @FIELD
to den ote “perfo r m this derive action on the selected fiel ds.” Using the expression log(@FIELD)
derives a new log field for each selected field.
Note: @ functions cannot be called from scripts .
Function
Result
Description
@FIELD
Any
Performs an action on all fields specified in
the expres sion context. Note that this function
cannot be called from a script.
@TARGET
Any
When a CLEM expression i s used in a
user-defined analysis function, @TARGET
represents the target field or “correct value” for
the target/predicted pair being analyzed. This
function is commonly used i n an Analysis node.
@PREDICTED
Any
When a CLEM expression i s used in a
user-defined analysis f unction,@PREDICTED
represents the predicted value for the
target/predicted pair being analyzed. This
function is commonly used i n an Analysis node.
@PARTITION_FIELD
Any
Substitutes the name of the current partition
field.
@TRAINING_PARTITION
Any
Returns the value of the current training
partition. For example, to select training records
using a Sel ect node, use the CLEM expression:
@PARTITION_FIELD = @TRAINING_PARTITION
This ensures that the Select node will always
work regar dless of which values are used to
represent each partition in the data.
@TESTING_PARTITION
Any
Returns the value of the current testing partition.
@VALIDATION_PARTITION
Any
Returns the value of the current valid at i on
partition.
@FIELDS_BETWEEN(start, end)
Any
Returns the list of field names between the
specified start and end fiel ds (inclusiv e) based
on the natural (that is, insert) order of the fields
in the data. For more information, see t he
topic Summarizing Multiple Fields in Chapter 7
on p. 115.
@FIELDS_MATCHING(pattern)
Any
Returns a list a field names matching a specified
pattern. A question mark (?) can be included in
the pattern t o match exactly one character; an
asterisk (*) matches zero or more characters. To
match a literal question mark or asterisk (rather
than using these as wildcards), a backslash
(\) can be used as an escape character. For
more information, see the topic Summarizing
Multiple Fields in Chapter 7 on p. 115.
@MULTI_RESPONSE_SET
Any
Returns the list of fields in the named multipl e
response set. For more information, see the
topic Working wit h Multiple-Resp onse Data in
Chapter 7 on p. 117.