# Chapter 4: Python Code for Creating files with `@originate`

See also

- Manual Table of Contents
- @transform syntax in detail
- Back to Chapter 4: @originate

## Using `@originate`

>     from ruffus import *

>     #---------------------------------------------------------------
>     #   create initial files
>     #
>     @originate([   ['job1.a.start', 'job1.b.start'],
>                    ['job2.a.start', 'job2.b.start'],
>                    ['job3.a.start', 'job3.b.start']    ])
>     def create_initial_file_pairs(output_files):
>         # create both files as necessary
>         for output_file in output_files:
>             with open(output_file, "w") as oo: pass

>     #---------------------------------------------------------------
>     #   first task
>     @transform(create_initial_file_pairs, suffix(".start"), ".output.1")
>     def first_task(input_files, output_file):
>         with open(output_file, "w"): pass

>     #---------------------------------------------------------------
>     #   second task
>     @transform(first_task, suffix(".output.1"), ".output.2")
>     def second_task(input_files, output_file):
>         with open(output_file, "w"): pass

>     #
>     #       Run
>     #
>     pipeline_run([second_task])

## Resulting Output

>         Job  = [None -> [job1.a.start, job1.b.start]] completed
>         Job  = [None -> [job2.a.start, job2.b.start]] completed
>         Job  = [None -> [job3.a.start, job3.b.start]] completed
>     Completed Task = create_initial_file_pairs
>         Job  = [[job1.a.start, job1.b.start] -> job1.a.output.1] completed
>         Job  = [[job2.a.start, job2.b.start] -> job2.a.output.1] completed
>         Job  = [[job3.a.start, job3.b.start] -> job3.a.output.1] completed
>     Completed Task = first_task
>         Job  = [job1.a.output.1 -> job1.a.output.2] completed
>         Job  = [job2.a.output.1 -> job2.a.output.2] completed
>         Job  = [job3.a.output.1 -> job3.a.output.2] completed
>     Completed Task = second_task