Comments on: Heuristics are easy http://cairnarvon.rotahall.org/2010/03/02/heuristics-are-easy/ Unscientific and ultimately destructive. Sun, 12 May 2013 14:59:20 +0000 hourly 1 http://wordpress.org/?v=3.5.1 By: Cairnarvon http://cairnarvon.rotahall.org/2010/03/02/heuristics-are-easy/comment-page-1/#comment-58346 Cairnarvon Sun, 01 Jan 2012 20:24:57 +0000 http://cairnarvon.rotahall.org/?p=1683#comment-58346 The second argument of sorted is a function that takes as its arguments two elements of the list to be sorted, and returns a negative number if the first is smaller than the second (according to some relevant ordering), zero if they’re equal, and a positive number if the first element is greater than the second.
sorted returns a new list, which is then joined to the tail of the queue (that is, all of the queue except for the first element; which is obtained using a list slice).

Longer way to write this would be:

def sort_function(element1, element2):
return h(element1[1]) - h(element2[1])

sorted_new_nodes = sorted(new_nodes, sort_function)
tail_of_queue = queue[1:]
queue = sorted_new_nodes + tail_of_queue

Hope that clarifies.

]]> By: AsianBorat http://cairnarvon.rotahall.org/2010/03/02/heuristics-are-easy/comment-page-1/#comment-58333 AsianBorat Sun, 01 Jan 2012 08:00:10 +0000 http://cairnarvon.rotahall.org/?p=1683#comment-58333 queue = sorted(new_nodes, lambda a, b: h(a[1]) – h(b[1])) + queue[1:]

How in hell does this line work? I read up on lambdas and sorted (I’m unfamiliar with Python), but I can’t make sense of this line.

]]> By: Anonymous http://cairnarvon.rotahall.org/2010/03/02/heuristics-are-easy/comment-page-1/#comment-45471 Anonymous Tue, 02 Mar 2010 18:49:52 +0000 http://cairnarvon.rotahall.org/?p=1683#comment-45471 Really enjoying these posts. Thanks.

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