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ExpressionProcessor

Bases: IDMixin

Tiles processor that computes a new channel from an expression

Experimental

ExpressionProcessor is experimental since 1.3.0 and may change without notice.

Additional dependencies

ExpressionProcessor requires the expression dependency group.

Notes

• Requires raster channels

Implements the TilesProcessor protocol.

PARAMETER	DESCRIPTION
expression_string	Expression string based on the numexpr expression syntax TYPE: str
new_channel_name	New channel name TYPE: ChannelName | str
max_num_threads	Maximum number of threads TYPE: int | None DEFAULT: None

id property

RETURNS	DESCRIPTION
uuid.UUID	ID

from_config classmethod

Creates an expression processor from the configuration.

PARAMETER	DESCRIPTION
config	Configuration TYPE: ExpressionProcessorConfig

RETURNS	DESCRIPTION
ExpressionProcessor	Expression processor

__call__

Computes the new channel from the expression.

PARAMETER	DESCRIPTION
tiles	Tiles TYPE: Tiles

RETURNS	DESCRIPTION
Tiles	Tiles

---

ExpressionProcessorConfig

Bases: pydantic.BaseModel

Configuration for the from_config class method of ExpressionProcessor

Create the configuration from a config file

• Use null instead of None

Usage

You can create the configuration from a config file.

config.yaml

package: 'aviary'
name: 'ExpressionProcessor'
config:
  expression_string: '(nir - r) / (nir + r)'
  new_channel_name: 'ndvi'
  max_num_threads: null

ATTRIBUTE	DESCRIPTION
expression_string	Expression string based on the numexpr expression syntax TYPE: str
new_channel_name	New channel name TYPE: ChannelName | str
max_num_threads	Maximum number of threads - defaults to None TYPE: int | None