petl_addons

This is a library that adds

Installation

pip install petl_addons

Usage

import petl_addons

apply

This patches the petl Table class with an apply method calls the specified function with the table. This allows pipeline fragments to be defined and applied in a clear format.

def filter_values(table):
    return table.selecteq('value', 10).selectnotnone('name')

table.apply(filter_values)

args and kwargs are passed through to the function:

def op(table, field, inflation=10):
    return table.convert(field, lambda f: f+inflation)

table.apply(op, 'value', inflation=20) // Will inflate the value field by 20

Multiple separate fragments can be chained together, greatly enhancing code readability and reusability.

table.apply(filter_values).apply(summarise_data).apply(write_csv)

The module also overloads the | character to allow the following usage, equivalent to the example above:

table | filter_values | summarise_data | write_csv

NB this won't work with parameter functions.

If you wish to load this on its own without any other modules, use the statement below.

import petl_addons.apply