> ## Documentation Index
> Fetch the complete documentation index at: https://docs.graphext.com/llms.txt
> Use this file to discover all available pages before exploring further.

# sum

> Calculate the row-wise sum of numeric columns. 

An additional constant may be used to add to the final result.

## Usage

The following examples show how the step can be used in a recipe.

<Accordion title="Examples" icon="code" defaultOpen="true">
  <Tabs>
    <Tab title="Example 1">
      To add columns `num1` and `num2`:

      ```stan theme={null}
      sum(ds.num1, ds.num2) -> (ds.total)
      ```
    </Tab>

    <Tab title="Example 2">
      To add the constant 3.141 to column `num1`:

      ```stan theme={null}
      sum(ds.num1, {"constant": 3.141}) -> (ds.num1_plus_pi)
      ```
    </Tab>

    <Tab title="Signature">
      General syntax for using the step in a recipe. Shows the inputs and outputs the step is expected to receive and will produce respectively. For futher details see sections below.

      ```stan theme={null}
      sum(*columns: number, {
          "param": value,
          ...
      }) -> (result: number)
      ```
    </Tab>
  </Tabs>
</Accordion>

## 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"`).

<Accordion title="Inputs" icon="right-to-bracket">
  <ParamField path="*columns" type="column[number]">
    One or numeric columns to sum.
  </ParamField>
</Accordion>

<Accordion title="Outputs" icon="right-from-bracket">
  <ParamField path="result" type="column[number]" required>
    Numeric column containing the result of the summation.
  </ParamField>
</Accordion>

## 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)`.

<Accordion title="Parameters" defaultOpen="true" icon="sliders">
  <ParamField path="constant" type="number" default="0">
    A constant to add.
  </ParamField>

  <ParamField path="ignore_nans" type="boolean" default="true">
    Whether to ignore NaNs or propagate them.
  </ParamField>
</Accordion>