Over a million developers have joined DZone.
{{announcement.body}}
{{announcement.title}}

Ruby/Python: Constructing a taxonomy from an array using zip

DZone's Guide to

Ruby/Python: Constructing a taxonomy from an array using zip

· DevOps Zone
Free Resource

The DevOps Zone is brought to you in partnership with Sonatype Nexus. The Nexus Suite helps scale your DevOps delivery with continuous component intelligence integrated into development tools, including Eclipse, IntelliJ, Jenkins, Bamboo, SonarQube and more. Schedule a demo today

As I mentioned in my previous blog post I’ve been hacking on a product taxonomy and I wanted to create a ‘CHILD’ relationship between a collection of categories.

For example, I had the following array and I wanted to transform it into an array of ‘SubCategory, Category’ pairs:

taxonomy = ["Cat", "SubCat", "SubSubCat"]
# I wanted this to become [("Cat", "SubCat"), ("SubCat", "SubSubCat")

In order to do this we need to zip the first 2 items with the last which I found reasonably easy to do using Python:

>>> zip(taxonomy[:-1], taxonomy[1:])
[('Cat', 'SubCat'), ('SubCat', 'SubSubCat')]

Here we using the python array slicing notation to get all but the last item of ‘taxonomy’ and then all but the first item of ‘taxonomy’ and zip them together.

I wanted to achieve that effect in Ruby though because my import job was written in that!

We can’t achieve the open ended slicing as far as I can tell so the following gives us an error:

> taxonomy[..-1]
SyntaxError: (irb):10: syntax error, unexpected tDOT2, expecting ']'
taxonomy[..-1]
           ^
	from /Users/markhneedham/.rbenv/versions/1.9.3-p327/bin/irb:12:in `<main>'

The way negative indexing works is a bit different so to remove the last item of the array we use ‘-2′ rather than ‘-1′:

> taxonomy[0..-2].zip(taxonomy[1..-1])
=> [["Cat", "SubCat"], ["SubCat", "SubSubCat"]]

The DevOps Zone is brought to you in partnership with Sonatype Nexus. Use the Nexus Suite to automate your software supply chain and ensure you're using the highest quality open source components at every step of the development lifecycle. Get Nexus today

Topics:

Published at DZone with permission of Mark Needham, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

THE DZONE NEWSLETTER

Dev Resources & Solutions Straight to Your Inbox

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.

X

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}