On Saturday, 1 October 2016 14:17:06 UTC+10, Rustom Mody wrote: > On Saturday, October 1, 2016 at 9:08:09 AM UTC+5:30, Sayth Renshaw wrote: > > I do like [(f + ['0'] if len(f) < 5 else f) for f in fups ] Rustom, if > > there are better non list comprehension options I would like to know as > > generally I find then confusing. > > Two points here — best taken independently: > 1. List comprehensions are confusing > 2. When to want/not want them > > > For 1 I suggest you (privately) rewrite them with '|' for 'for' and '∈' for > 'in' > Once you do that they will start looking much more like the origin that > inspires > them — set builder notation: > https://en.wikipedia.org/wiki/Set-builder_notation > > From there I suggest you play with replacing '[]' with '{}' ie actually try > out set comprehensions and then others like dict-comprehensions — very nifty > and oft-neglected. And the mother of all — generator comprehensions. > > Of course to check it out in python you will need to invert the translation: > '|' for 'for' and '∈' for 'in' > the point of which is to use python as a kind of math assembly language > *into* which you *code* but not in which you *think* > > For 2 its important that you always keep in front of you whether you want to > approach a problem declaratively (the buzzword FP!) or imperatively. > Python is rather unique in the extent to which it allows both > This also makes it uniquely difficult because its all too easy to garble the > two styles as John's .append inside a LC illustrates. > > And the way to ungarble your head is by asking yourself the meta-question: > Should I be asking "How to solve this (sub)problem?" or more simply > "What is the (sub)problem I wish to solve?" > > How questions naturally lead to imperative answers; whats to declarative > > You may be helped with [plug!] my writings on FP: > http://blog.languager.org/search/label/FP > > Particularly the tables in: > http://blog.languager.org/2016/01/primacy.html
Thank You Rustom -- https://mail.python.org/mailman/listinfo/python-list
