When a Python transformation reads input rows, it converts incoming field data types to Python data types. When a Python transformation writes output rows, it converts Python data types to output field data types.

For example, the following processing occurs for an input field with the double data type:

The Python transformation converts the double data type in the incoming field to the Python float data type.
The Python transformation uses the value in the incoming field as the value for the Python float data type.
When the transformation generates the output row, it converts the Python float data type to the double data type.

The following table shows how the Python transformation maps transformation data types to Python data types:

Transformation data type	Python data type
Integer	Int
Decimal	Float
Double	Float
Timestamp	Datetime
String	Str
text	Text