String Indexer
===========

StringIndexer encodes a string column of labels to a column of label indices

Input
--------------
It takes in a DataFrame and transforms it to another DataFrame

Output
--------------
It adds a new column containing the encoding of the string column of labels to a column of label indices, to the incoming DataFrame.

Type
--------- 

ml-transformer

Class
--------- 

fire.nodes.etl.NodeStringIndexer

Fields
--------- 

.. list-table::
      :widths: 10 5 10
      :header-rows: 1

      * - Name
        - Title
        - Description
      * - inputCol
        - Input Columns
        - Input column
      * - outputCol
        - Output Column
        - Output column


Details
-------
String Indexer Node Details
+++++++++++++++


The String Indexer Node is used to encode a string column of labels to a column of label indices. It takes in a DataFrame and transforms it to another DataFrame by adding a new column containing the encoding of the string column of labels to a column of label indices.

It takes in the parameters handleInvalid, inputCol and outputCol, which are used to handle invalid entries, input column name and output column name respectively.



Input Parameters
+++++++++++++++


HANDLE INVALID: Select whether to skip or throw error on invalid entries.

INPUT COLUMN: Select the required column for encoding.

OUTPUT COLUMN: The name of the output column after encoding.


Examples
-------
String Indexer Node Example
+++++++++++++++


Consider the below **String Indexer** output for the **color** column


id color encoded_color

0   red     2

1   green   1

2   blue    0

3   purple  3


In this example, the input column is color and the output column is encoded_color. The string indexer encodes the color column to a column of label indices. The handleInvalid is set to skip, so any invalid entries will be skipped.