It takes a list of user-defined rules from the second input port (from the selected column(s)) and tries to match them to each row in the input table. If a rule matches, its outcome value is added into a new column. The first matching rule in order of definition determines the outcome.
Each rule is represented by a row, new line characters are replaced by spaces, even in string constants.
To add comments, start a line in a (condition) cell with
//
(comments can not be placed in the same line as a rule). Anything after // will not be interpreted as a rule.
Rules consist
of a condition part (antecedent), which must evaluate to
true or false, and an outcome (consequent, after the => symbol) which is
put into the new column if the rule matches.
The outcome of a rule may be any of the following: a string (between quotes
" or /), a number, a boolean constant, a reference to another column or the value of
a flow variable value.
The type of the outcome column is the common super type of all possible outcomes (including the rules
that can never match). If no rule matches, the outcome is a missing value unless a default value
is specified.
Columns are given by their name surrounded by $, numbers are given in the usual decimal representation. Note that strings must not contain (double-) quotes. Flow variables are represented by $${TypeCharacterAndFlowVarName}$$. (Column references are not supported for PMML outputs.) The TypeCharacter should be 'D' for double (real) values, 'I' for integer values and 'S' for strings.
The logical expressions can be grouped with parentheses. The precedence rules for them are the
following:
NOT
binds most,
AND
,
XOR
and finally
OR
the least. Comparison operators always take precedence over logical connectives. All operators (and
their names) are case-sensitive.
The
ROWID
represents the row key string, the
ROWINDEX
is the index of the row (first row has
0
value), while
ROWCOUNT
stands for the number of rows in the table. (These are not available for PMML.)
Some example rules (each should be in one row):
// This is a comment $Col0$ > 0 => "Positive"When the values in Col0 are greater than 0, we assign Positive to the result column value (if no previous rule matched).
$Col0$ = "Active" AND $Col1$ <= 5 => "Outlier"You can combine conditions.
$Col0$ LIKE "Market Street*" AND
($Col1$ IN ("married", "divorced")
OR $Col2$ > 40) => "Strange"
$Col0$ MATCHES $${SFlowVar0}$$ OR $$ROWINDEX$$ < $${IFlowVar1}$$ =>
$Col0$
With parentheses you can combine multiple conditions. The result in the second case comes from one of the
columns.
$Col0$ > 5 => $${SCol1}$$
The result can also come from a flow variable.
The following comparisons result true (other values are neither less, nor greater or equal to missing and NaN values):
- ? =,<=,>= ?
- NaN =,<=,>= NaN
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Workflows
03_OpenSourceVizAndModelingKNIME Hub- 07 matching non matching stringsKNIME Hub
- 09_DataVisualization_AirlineDatasetKNIME Hub
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Links
- Alteryx to KNIME conversionby HansS on 2024-09-30forum.knime.com/p/270563
- Merge two datasets and have new column outputby armingrudd on 2020-03-10forum.knime.com/p/83878
- How to more elegantly replace strings in bulk using wildcards?by izaychik63 on 2020-06-08forum.knime.com/p/93752
- Rule Engine Auto Updateby AnotherFraudUser on 2020-05-21forum.knime.com/p/91997
- Rule Engine - keywords as variableby izaychik63 on 2023-06-19forum.knime.com/p/213555
- Show all 16 links
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