Writing your first kedro Nodes

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Before we jump in with anything crazy, let's make some nodes with some vanilla data structures.

import node

You will need to import node from kedro.pipeline to start creating nodes.

from kedro.pipeline import node

func

The func is a callable that will take the inputs and create the outputs .

inputs / outputs

Inputs and outputs can be None, a single catalog entry as a string, mutiple catalog entries as a List of strings, or a dictionary of strings where the key is the keyword argument of the func and the value is the catalog entry to use for that keyword.

our first node

Sometimes in our pipelines our data is coming from an api where we already have python functions built to pull with. Thats ok, kedro supposrts that with inputs=None .

def create_range():
    return range(100)

make_range = node(
    func=create_range,
    inputs=None,
    outputs='range'
    )

second node

Now we have some data to work from, lets use that as our input.

def square_range():
    return [i**2 for i in range]

square_range = node(
    func=square_range,
    inputs='range',
    outputs='range_squared'
    )

Multiple Inputs

Kedro can take lists or dicts as either input or output when your function needs more than one input or output.

def concat(range, range_two):
    return [*range, *range_two]

concat_ranges = node(
    func=concat,
    inputs=['range', 'range_squared']
    outputs='concat'
    )

## inputs could also be defined as a dict
concat_ranges = node(
    func=concat,
    inputs={'range': 'range', 'range_two': 'range_squared'}
    outputs='concat'
    )


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