This node evaluates a mathematical expression based on
the values in a row. The computed results can be either appended as
new column or be used to replace an input column. Available variables
are the values in the corresponding row of the table (left list
in the dialog). Commonly used functions are shown in the list
"Mathematical Functions". There are also some constants available,
such as *pi* (the ratio of the circumference of a circle
to its diameter), *e* (the base of the natural logarithms), the total
number of rows in the table, and some other column based constants
(`constant`

category of functions).

This node uses *JEP*, the
Java Math Expression Parser.

Column based constants such as *COL_MIN(col_name)* will be calculated in advance (if necessary).

You can reference the integer flow variables like this: `$${IflowVar}$$`

,
the floating point flow variables like this: `$${DflowVar}$$`

.

Reference the columns with the form: `$colName$`

When any of the used columns contains a missing value, the result is missing, just like when the result would be NaN, infinite value, or outside of the 32 bit signed integer range when that is requested.

NaN values act as value true in boolean expressions and compared to anything (including NaN) in any way (including ==, but not !=, which is like !(... == ...)) is false (0).

*Please note the expressions are case sensitive.*

- Column List
- Available numerical columns, which can be used as variables in the expression.
- Flow Variable List
- Available flow variables, which can be used as variables in the expression.
- Category
- The operator categories.
- Function
- A list of valid operators in the selected category.
- Description
- Short help about the operator.
- Expression
- The mathematical expression editor. You have completion available.
- Append Column
- The name of the column to append.
- Replace Column
- The column to be replaced.
- Convert to Int
- The result should be converted to an integer, or kept as a floating point number.

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You want to see the source code for this node? Click the following button and we’ll use our super-powers to find it for you.

To use this node in KNIME, install the extension KNIME Math Expression (JEP) from the below update site following our NodePit Product and Node Installation Guide:

v4.6

A zipped version of the software site can be downloaded here.

Do you have feedback, questions, comments about NodePit, want to support this platform, or want your own nodes or workflows listed here as well? Do you think, the search results could be improved or something is missing? Then please get in touch! Alternatively, you can send us an email to mail@nodepit.com, follow @NodePit on Twitter, or chat on Gitter!

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