Python module to iterate with two sets of keys

Sun 2025/03/09 Python python / utilties

Overview

• installation: see https://arrizza.com/setup-common.html

Summary

This project is for content that needs to be iterated in two different ways. It allows two keys ("left" and "right") to be defined at the same time.

How to use

load()

Use load(path) to load a json file. Use load(path, validate=True) to check for duplicate keys.

Sample json content is:

[
    [
        "left3",    # <== the "left" key
        "right2",   # <== the "right" key
        "infoA"     # <== info for this entry & keys; Can be "null" if there is no info
    ],
    [
        "left2",
        "right3",
        null
    ],
]

save()

Use save(path) to save the current content to a json file.

add()

Use add(left, right, info) to add a new entry. The left and right keys have to be unique, otherwise an exception is thrown.

Note that info is optional add(left, right) or explicitly set to None.

all_by_left() and all_by_right()

To iterate in sorted order by the left key, use:

pds = PyDualSorter()
pds.load('path/to/file')
for left, right, info in pds.all_by_left():
    print(f'left key is  {left}')
    print(f'right key is {left}')
    print(f'info is      {info}')

To iterate in sorted order by the right key, use:

pds = PyDualSorter()
pds.load('path/to/file')
for left, right, info in pds.all_by_left():   # <== note that left key is still present
    print(f'left key is  {left}')
    print(f'right key is {left}')
    print(f'info is      {info}')

is_left() and is_right()

Use is_left(val) to check if a value is a left key. Use is_right(val) to check if a value is a right key.

get_left_info() and get_right_info()

Use info = pds.get_left_info(left) to get the info associated with the given left key. Use info = pds.get_right_info(right) to get the info associated with the given right key.

get_left() and get_right()

Use right = pds.get_right(left) to get the matching right key for the given left key. Use left = pds.get_left(right) to get the matching left key for the given right key.