2011/8/1 Dhananjay Nene <dhananjay.n...@gmail.com>: > On Mon, Aug 1, 2011 at 4:17 PM, Anand Chitipothu <anandol...@gmail.com> wrote: >> 2011/8/1 Dhananjay Nene <dhananjay.n...@gmail.com>: >>> On Sat, Jul 30, 2011 at 2:15 PM, Asif Jamadar <asif.jama...@rezayat.net> >>> wrote: >>>> What if I have two lists for both minimum and maximum values >>>> >>>> Minimum Maximum >>>> 0 10 >>>> 11 20 >>>> 21 30 >>>> 31 40 >>>> >>>> >>>> Now how should I check if actual result is not laying between above ranges >>>> >>>> if not minimum<=actual_result and not maximum>=actual_result: >>>> >>>> Any suggestions? >>> >>> def in_range(number) : >>> return any(map(lambda (x,y) : x <= number <= y, >>> ((0,10),(11,20), (21,30), (31,40)))) >> >> How about this? >> >> def in_range(number, min_max_pairs): >> return any(x <= number <=y for x, y in min_max_pairs) > > Definitely better >> >> List comprehensions and generation expressions are usually more >> readable and expressive than using map. > > Thats probably truer for the python and python trained eyes than any > other (in other words its both subjective and contextual and a bit to > do with syntax). Allow me to illustrate : > > If I want to double all elements in a list and then increment them by > one, here's how I would use a map in python > > def double(x) : return x * 2 > def increment(x) : return x + 1 > print map(increment,map(double,range(5))) > > and here's how I would do it in scala - notice the last (third) line > and consider its readability (I'm sure a scala non-novice will offer > something even superior) > > def double(n: Int) = n * 2 > def increment(n: Int) = n + 1 > println(0 to 4 map double map increment) > > so readability is often a function of what one's eyes are trained ot > read and also the syntactic capabilities in the language
This is just the prefix/postfix thing. Yes, prefix style is difficult to read if there are too many nested levels. Look at lisp code for example. Yes, it feel it awkward when I have to do range(len(x)). Unix pipes and chaining methods are postfix. What you are doing in scala is just that. If map was a list method, I could do this: range(0, 4).map(douple).map(increment) And as unix pipe: seq 0 4 | double | increment > I also find map much more atomic and portable construct to think in - > after all every list comprehension is syntactic sugar around map + > filter, and map/reduce/filter are far more omnipresent than list > comprehensions. Recently, I was thinking about converting a list comprehension to map/filter calls and It turned out that list comprehensions are more than map+filter. [i * i for i in range(10)] ~ map(lambda i*i, range(10)) [i * i for i in range(10) if i % 2 == 0] ~ map(lambda i*i, filter(lambda i%2 == 0, range(10))) But the situation gets tricky when there are multiple loop items in the list comprehension. Here is a list comprehension to find all Pythagorean triplets below 100. [(x, y, z) for x in range(1, 50) for y in range(x, 100) for z in range(y, 100) if x*x + y*y == z*z] Try converting this into map/filter and you'll understand the difference. Anand _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers
