Comments on: Groovy reverse map sort done easy

By: TheKaptain

TheKaptain — Thu, 14 Jan 2010 05:37:31 +0000

Yeah, wordpress can sometimes be too ‘helpful’ that way. And you’re absolutely right – shame on me for assuming that order was part of the comparison; the assertion I’ve shown is only relevant as far as the items in the map, not their order. I think you’ll find this, however, does properly check that condition.

def map = [a:3, b:2, c:1]
map = map.sort {it.value}
assert (map.keySet() as List) == ['c','b','a']

By: Keegan

Keegan — Thu, 14 Jan 2010 02:14:51 +0000

Sorry, looks like wordpress cut my example off, what I had in square brackets was a:3, c:1, b:2

By: Keegan

Keegan — Wed, 13 Jan 2010 21:43:16 +0000

Oops, I must have forgot to do the reassignment. Sorry about that. My statement about the asserts is still true, as someone pointed out to me today (I made the same mistake). For example, put this at the end assert map == [c 1="a:1," 2="b:2" language=":3,"][/c] and you'll see it too passes. Your assert is good for demonstrating, just something to keep in mind.

By: TheKaptain

TheKaptain — Wed, 13 Jan 2010 17:02:18 +0000

Not sure exactly what you mean here Keegan…
The sort method returns a new Map instead of sorting the existing map – perhaps that’s what you’re seeing if you’re still examining the original Map?
Adding some println’s to the code above I see these results:
Sorting by key before sort – a:3, b:2, c:1
Sorting by key after sort – c:1,b:2,a:3
Sorting by value before sort – a:1, b:2, c:3
Sorting by value after sort – c:3,b:2,a:1

By: Keegan

Keegan — Wed, 13 Jan 2010 16:27:51 +0000

Your assertion passes, but it doesn’t compare order. I tried this in Groovy 1.6.7 and 1.7.0 and the order was unchanged from the original. (Compared println of the map to the original). Am I missing something?