calculate
Evaluates a formula containing basic arithmetic over a dataset’s columns.
For example, to multiply column A by two and add column Col B, you would simply write
For more details regarding valids operators etc. see the Pandas eval() documentation, more specifically the supported syntax, and eval() applied to DataFrames.
Note that assignments in the formula are not supported, since the result must always be a new column,
i.e. the following kind of formula should be avoided: "c = a + b". The correct way to return the result
as a column would simply be "a + b".
If the name of an input column contains spaces, such as in the example above, it should be quoted in single backticks.
Usage
The following example shows how the step can be used in a recipe.
Assuming a dataset ds containing the numeric columns num_a, num_b and num_c, and a constant a with value 1.3, the following formula transforms each column numerically before adding and multiplying them together, all in one step:
Inputs & Outputs
The following are the inputs expected by the step and the outputs it produces. These are generally
columns (ds.first_name), datasets (ds or ds[["first_name", "last_name"]]) or models (referenced
by name e.g. "churn-clf").
Configuration
The following parameters can be used to configure the behaviour of the step by including them in
a json object as the last “input” to the step, i.e. step(..., {"param": "value", ...}) -> (output).
The formula to execute. A formula containing basic arithmetic operations and references to column names.
Constants to be used in the formula.
An object of key-value pairs, where keys refer to names of constants whose values will be available
in the formula with a @ prefix. E.g. "constants": {"factor": 1.23} makes it possible to refer to
@factor in the formula with given value; also see example(s).
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