Comments on: Python 3.1, you shouldn’t have!

By: Malthe

Malthe — Thu, 02 Jul 2009 11:21:03 +0000

I agree; either one of them. Certainly “itemgetter“ is more efficient, too.

By: Christopher Leary

Christopher Leary — Thu, 02 Jul 2009 11:14:47 +0000

@Malthe: I think it has distilled down to a difference of opinion. As I see it, frequency_key is a meaningless function outside of the context where you have a sequence with the second element being a frequency value. I personally find that function more objectionable because its name implies some sort of generality, whereas the anonymous function is intentionally throw-away in the (temporary) item-iteration context.

Overall, I’m partial to an inline “itemgetter(1)“, as mentioned by @xtian — less ugly than a lambda, plus stdlib-approved and -documented.

By: Malthe

Malthe — Thu, 02 Jul 2009 10:01:39 +0000

Lennart’s version is much more readable, which is entirely what counts.

By: xtian

xtian — Thu, 02 Jul 2009 07:27:51 +0000

itemgetter(1) is much nicer than lambda t: t[1] (it lives in the operator module).

By: Christopher Leary

Christopher Leary — Thu, 02 Jul 2009 04:35:08 +0000

@Lennart: I’m willing to accept that the dict comprehension may be better written as a for loop (due to stdin side effects), but I don’t agree with the elimination of the lambda. Really simple one-statement operations (like sequence indexing in a throw-away sort invocation) are the few cases where I’ll actually prefer an anonymous function — I’m pretty sure that’s the use case that caused lambdas to remain in the language in the transition to Py3k.

@Roberto @rgz: You guys are totally right. Been writing too much 2.x compatible code lately. ;-) Updated to reflect your correction!

By: rgz

rgz — Thu, 02 Jul 2009 01:05:42 +0000

Instead of

    birthday = dict((part, int(input('Enter birth {}: '.format(part))))
        for part in 'year mbirthday = dict((part, int(input('Enter birth {}: '.format(part))))
        for part in 'year month day'.split())
    onth day'.split())

what about

    birthday = {part: int(input('Enter birth {}: '.format(part)))
        for part in 'year mbirthday = dict((part, int(input('Enter birth {}: '.format(part))))
        for part in 'year month day'.split())
    onth day'.split()}

By: Roberto Bonvallet

Roberto Bonvallet — Thu, 02 Jul 2009 00:07:50 +0000

You’re missing dict comprehensions :)

birthday = {part: int(input('Enter birth {}: '.format(part)))
    for part in 'year month day'.split()}

By: Lennart Regebro

Lennart Regebro — Wed, 01 Jul 2009 21:54:16 +0000

Ough, the obfuscation! It hurtz!

There, I fixed it. ;-)

#!/usr/bin/env python3.1
 
import collections
import datetime
 
 
birthday = {}
for part in ('year', 'month', 'day'):
    birthday[part] = int(input('Enter birth {}: '.format(part)))
 
now = datetime.datetime.now()
days = []
for year in range(birthday['year'], now.year + 1):
    date = datetime.date(year, birthday['month'], birthday['day'])
    days.append(date.strftime('%A'))
 
def frequency_key(t):
    return t[1]
 
counter = collections.Counter(days)
fmt = '{:15} {:>3}'
for day, frequency in sorted(counter.items(), key=frequency_key, reverse=True):
    print(fmt.format(day, frequency))
print(fmt.format('Total', sum(counter.values())))