LazyArray#

This is an API interface for evaluating an expression or a Python user defined function.

You can get an object following the LazyArray API with any of the following ways:

Any expression that involves one or more NDArray objects. e.g. a + b, where a and b are NDArray objects (see a tutorial).
Using the lazyexpr constructor.
Using the lazyudf constructor (see a tutorial).

The LazyArray object is a thin wrapper around the expression or user-defined function that allows for lazy evaluation. This means that the expression is not evaluated until the compute or __getitem__ methods are called. The compute method will return a new NDArray object with the result of the expression evaluation. The __getitem__ method will return an NumPy object instead.

See the LazyExpr and LazyUDF sections for more information.

Methods#

`__getitem__`	Return a NumPy.ndarray containing the evaluation of the LazyArray.
`compute`	Return an NDArray containing the evaluation of the LazyArray.
`save`	Save the LazyArray on disk.

LazyExpr#

An expression like a + sum(b), where there is at least one NDArray object in operands a and b, returns a LazyExpr object. You can also get a LazyExpr object using the lazyexpr constructor (see below).

This object follows the LazyArray API for evaluation and storage.

lazyexpr

Get a LazyExpr from an expression.

Utilities#

A series of utilities are provided to work with LazyExpr objects.

`validate_expr`	Validate expression for forbidden syntax and valid method names.
`get_expr_operands`	Given an expression in string form, return its operands.

LazyUDF#

For getting a LazyUDF object (which is LazyArray-compliant) from a user-defined Python function, you can use the lazyudf constructor below. See a tutorial on how this works.

This object follows the LazyArray API for evaluation, although storage is not supported yet.

lazyudf

Get a LazyUDF from a python user-defined function.