R: Create Dummy Variables

ml_create_dummy_variables {sparklyr} | R Documentation

## Create Dummy Variables

### Description

Given a column in a Spark DataFrame, generate a new Spark DataFrame containing dummy variable columns.

### Usage

    ml_create_dummy_variables(x, input, reference = NULL, levels = NULL,
      labels = NULL, envir = new.env(parent = emptyenv()))

### Arguments

`x` | An object coercable to a Spark DataFrame (typically, a `tbl_spark`).
`input` | The name of the input column.
`reference` | The reference label. This variable is omitted when generating dummy variables (to avoid perfect multi-collinearity if all dummy variables were to be used in the model fit); to generate dummy variables for all columns this can be explicitly set as `NULL`.
`levels` | The set of levels for which dummy variables should be generated. By default, constructs one variable for each unique value occurring in the column specified by `input`.
`labels` | An optional R list, mapping values in the `input` column to column names to be assigned to the associated dummy variable.
`envir` | An optional R environment; when provided, it will be filled with useful auxiliary information. See Auxiliary Information for more information.

### Details

The dummy variables are generated in a similar mechanism to `model.matrix`, where categorical variables are expanded into a set of binary (dummy) variables. These dummy variables can be used for regression of categorical variables within the various regression routines provided by `sparklyr`.

### Auxiliary Information

The `envir` argument can be used as a mechanism for returning optional information. Currently, the following pieces are returned:

`levels`: | The set of unique values discovered within the input column.
`columns`: | The column names generated.

If the `envir` argument is supplied, the names of any dummy variables generated will be included, under the `labels` key.

[Package sparklyr version 0.5.4 Index]