@Marvin I want to do some data processing where I want to map over a list, process the items with one task, and then each result with the next task. How do I do that in Prefect 3?

In Prefect 3, you can achieve the desired data processing workflow by using the

@task

decorator to define tasks and the

@flow

decorator to manage the flow of tasks. Here's a concise way to map over a list, process items with one task, and then process each result with the next task: 1. Define Tasks: Use the

@task

decorator to define each processing step as a task. 2. Map and Chain Tasks: Use the

map

method to apply a task to each item in a list. Then, chain the tasks by using the output of one task as the input to the next. Here's a simple example:

python
from prefect import flow, task

@task
def process_item(item):
    # Your processing logic here
    return item * 2

@task
def further_process(result):
    # Further processing logic
    return result + 1

@flow
def process_data(data):
    # Map over the list
    processed_items = process_item.map(data)
    # Further process each result
    final_results = further_process.map(processed_items)
    return final_results

# Example usage
data = [1, 2, 3, 4]
results = process_data(data)

This code sets up a data processing pipeline where

process_item

is applied to each element of

data

, and then

further_process

is applied to each result. The

map

method is key to applying tasks over lists in Prefect. For more details, you can refer to the Prefect tasks documentation.