Profile

Cover photo
Tasos Latsas
Works at Pamediakopes.gr
Attended Kingston University
75 followers|30,306 views
AboutPostsPhotosYouTube

Stream

Tasos Latsas

Shared publicly  - 
 
 
I was asked on Twitter why Python uses 0-based indexing, with a link to a new (fascinating) post on the subject (http://exple.tive.org/blarg/2013/10/22/citation-needed/). I recall thinking about it a lot; ABC, one of Python's predecessors, used 1-based indexing, while C, the other big influence, used 0-based. My first few programming languages (Algol, Fortran, Pascal) used 1-based or variable-based. I think that one of the issues that helped me decide was slice notation.

Let's first look at use cases. Probably the most common use cases for slicing are "get the first n items" and "get the next n items starting at i" (the first is a special case of that for i == the first index). It would be nice if both of these could be expressed as without awkward +1 or -1 compensations.

Using 0-based indexing, half-open intervals, and suitable defaults (as Python ended up having), they are beautiful: a[:n] and a[i:i+n]; the former is long for a[0:n].

Using 1-based indexing, if you want a[:n] to mean the first n elements, you either have to use closed intervals or you can use a slice notation that uses start and length as the slice parameters. Using half-open intervals just isn't very elegant when combined with 1-based indexing. Using closed intervals, you'd have to write a[i:i+n-1] for the n items starting at i. So perhaps using the slice length would be more elegant with 1-based indexing? Then you could write a[i:n]. And this is in fact what ABC did -- it used a different notation so you could write a@i|n.(See http://homepages.cwi.nl/~steven/abc/qr.html#EXPRESSIONS.)

But how does the index:length convention work out for other use cases? TBH this is where my memory gets fuzzy, but I think I was swayed by the elegance of half-open intervals. Especially the invariant that when two slices are adjacent, the first slice's end index is the second slice's start index is just too beautiful to ignore. For example, suppose you split a string into three parts at indices i and j -- the parts would be a[:i], a[i:j], and a[j:].

So that's why Python uses 0-based indexing.
1
Add a comment...

Tasos Latsas

Shared publicly  - 
1
Add a comment...

Tasos Latsas

Shared publicly  - 
 
 
Amazing photos of US cities in the early 1900s by airship: http://chi.mg/10IMAtq
1
Add a comment...

Tasos Latsas

Shared publicly  - 
 
Fixing good ol' reliable. This was my first laptop, and after 6 (I think) years it urgently needed some cleaning and thermal paste. It was getting hot, around 60-65°C when idle, just after the boot process.

The operation was a success as it now gets around 35° on idle and around 60° on high load. Hopefully in a few days it might drop a little more as the thermal paste reaches its optimal thermal conductivity.
4
Alfredo Palhares's profile photoJelle van der Waa's profile photoTasos Latsas's profile photo
3 comments
 
Nice, another achievement unlocked
Add a comment...

Tasos Latsas

Shared publicly  - 
 
 
A walk around the #io13  floor...
1
Add a comment...
Have him in circles
75 people
Achilleas Pipis's profile photo
Evangelos Koutsourakis's profile photo
Marialena Grigoraki's profile photo
David Vazgenovich Shakaryan's profile photo
maria karoutsou's profile photo
Scott Garrett's profile photo
 
This is going to be epic!
1
Add a comment...

Tasos Latsas

Shared publicly  - 
 
Some random photos from the amazing euruko 2013.
1
Add a comment...
 
 
Meet the new Google Maps: built to be smarter and more immersive. Each time you click or search, our new technology draws you a tailored map that highlights the information you need. Learn more: http://goo.gl/93IFB

Want to be among the first to experience the new desktop Google Maps? Request an invite at www.google.com/maps/preview

  #newgooglemaps #io13 #googleio
1
Add a comment...

Tasos Latsas

Shared publicly  - 
2
1
Alfredo Palhares's profile photo
Add a comment...
People
Have him in circles
75 people
Achilleas Pipis's profile photo
Evangelos Koutsourakis's profile photo
Marialena Grigoraki's profile photo
David Vazgenovich Shakaryan's profile photo
maria karoutsou's profile photo
Scott Garrett's profile photo
Work
Occupation
Software Engineer
Employment
  • Pamediakopes.gr
    Software engineer, present
  • Flipnode LLC
    Software engineer, 2013 - 2014
  • Technological Educational Institute of Athens
    Developer and Sysadmin, 2011 - 2012
Basic Information
Gender
Male
Other names
tasidus at freenode
Story
Introduction
Linux, Open Source, Hackerspaces, Web, APIs, CodeClubs, Beer, Music, Sci-Fi, Animes.
Education
  • Kingston University
    Networking and Data Communications
  • Technological Educational Institute of Athens
    Computer Science