bit of help with n-ary please...
Hi, Ok what im trying to do is replace an element in an n-ary and display the completed tree. So this is what ive got so far. data Tree a = Empty |Leaf a|Branch a [Tree a] deriving (Show) replace :: Eq a=>a->a->Tree a -> (Tree a) replace x y Empty = Element x replace x y (Leaf z) | x==z = (Leaf y) -- | otherwise = replace x y (Branch z lis) | x==z = (Branch y lis) |otherwise = replaceA x y clis replaceA :: Eq a=> a->a->[Tree a]->(Tree a) replaceA _ _ [] = Empty -- run out replaceA x y (h:r) |Q suc = suc |otherwise = replaceA x y r where suc=replace x y h Q :: a -> Bool Q a = True Q a = False Theres two main problems i am having. One is I'm not sure what should be the "otherwise" in the leaf function. Another problem is it doesn't show the whole tree just the part after the replacement. If you think this is complete bull I'll quite happily start over if somebody could give me some insight into what is the best way of tackling this problem is. Many thanks in advance spot -- View this message in context: http://old.nabble.com/bit-of-help-with-n-ary-please...-tp26258006p26258006.h... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
Anybody? thanks spot135 wrote:
Hi,
Ok what im trying to do is replace an element in an n-ary and display the completed tree.
So this is what ive got so far.
data Tree a = Empty |Leaf a|Branch a [Tree a] deriving (Show)
replace :: Eq a=>a->a->Tree a -> (Tree a)
replace x y Empty = Element x
replace x y (Leaf z) | x==z = (Leaf y) -- | otherwise =
replace x y (Branch z lis) | x==z = (Branch y lis) |otherwise = replaceA x y clis
replaceA :: Eq a=> a->a->[Tree a]->(Tree a) replaceA _ _ [] = Empty -- run out replaceA x y (h:r) |Q suc = suc |otherwise = replaceA x y r where suc=replace x y h
Q :: a -> Bool Q a = True Q a = False
Theres two main problems i am having. One is I'm not sure what should be the "otherwise" in the leaf function. Another problem is it doesn't show the whole tree just the part after the replacement.
If you think this is complete bull I'll quite happily start over if somebody could give me some insight into what is the best way of tackling this problem is.
Many thanks in advance
spot
-- View this message in context: http://old.nabble.com/bit-of-help-with-n-ary-please...-tp26258006p26259268.h... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
I don't know if this is homework. I suppose what you mean is the following: I'm trying to replace an element in an n-ary tree and display the completed tree. A more precise specification might help. - is the tree ordered - are all the elements in the leaves (not internal nodes) - is the location of the element to be replaced given? -- if so how? - is the tree supposed to be balanced? On Sun, 8 Nov 2009 15:40:03 -0800 (PST), you wrote:
Anybody? thanks
spot135 wrote:
Hi,
Ok what im trying to do is replace an element in an n-ary and display the completed tree.
So this is what ive got so far.
<snip> -- Regards, Casey
Hi Casey, Answers to spec. the tree is not ordered, it holds string varying in length. the element value is given, but not its location ie (replace "Two" "Five" Tree a) would find the location of element "Two" and replace it with "Five" the tree is not balanced, Nodes can have other Nodes coming off them as well as Leaves, the number of leaves per node vary as well. Is that ok? Casey Hawthorne wrote:
I don't know if this is homework.
I suppose what you mean is the following: I'm trying to replace an element in an n-ary tree and display the completed tree.
A more precise specification might help. - is the tree ordered - are all the elements in the leaves (not internal nodes) - is the location of the element to be replaced given? -- if so how? - is the tree supposed to be balanced?
On Sun, 8 Nov 2009 15:40:03 -0800 (PST), you wrote:
Anybody? thanks
spot135 wrote:
Hi,
Ok what im trying to do is replace an element in an n-ary and display the completed tree.
So this is what ive got so far.
<snip>
-- Regards, Casey _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- View this message in context: http://old.nabble.com/bit-of-help-with-n-ary-please...-tp26258006p26259580.h... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
Answers to spec.
You didn't answered the "homework" question:
I don't know if this is homework.
I'm a bit suspicious: http://www.dcs.shef.ac.uk/intranet/teaching/modules/level2/com2010.html . See http://www.haskell.org/haskellwiki/Homework_help . Cheers, Stefan
On Mon, Nov 9, 2009 at 12:31 AM, Stefan Holdermans
Answers to spec.
You didn't answered the "homework" question:
I don't know if this is homework.
I'm a bit suspicious: http://www.dcs.shef.ac.uk/intranet/teaching/modules/level2/com2010.html .
This is the typical bottled response to people asking for homework help. But spot135 has done a good job so far: stated his problems, shown his work so far, asking for guidance not answers. And the community has done a good job helping: no answers, but hints and leading questions. I would say, so far, this has been a "textbook example" of a homework exchange. Luke
Luke,
This is the typical bottled response to people asking for homework help. But spot135 has done a good job so far: stated his problems, shown his work so far, asking for guidance not answers. And the community has done a good job helping: no answers, but hints and leading questions. I would say, so far, this has been a "textbook example" of a homework exchange.
Agreed. But still... I think that one (if that's the case) should clearly indicate that their question relates to homework. [No desire to fork this thread into an extensive discussion on homework help, though.] Cheers, Stefan
Am Sonntag 08 November 2009 23:24:59 schrieb spot135:
Hi,
Ok what im trying to do is replace an element in an n-ary and display the completed tree.
So this is what ive got so far.
data Tree a = Empty |Leaf a|Branch a [Tree a] deriving (Show)
replace x y tree should give a tree with the same structure, values equal to x should be replaced by y, all other values left as they are?
replace :: Eq a=>a->a->Tree a -> (Tree a)
replace x y Empty = Element x
That should surely be replace _ _ Empty = Empty ?
replace x y (Leaf z)
| x==z = (Leaf y)
-- | otherwise =
| otherwise = Leaf z
replace x y (Branch z lis)
| x==z = (Branch y lis) |otherwise = replaceA x y clis
You'd want to recur, I believe, use map (replace x y)
replaceA :: Eq a=> a->a->[Tree a]->(Tree a) replaceA _ _ [] = Empty -- run out replaceA x y (h:r)
|Q suc = suc |otherwise = replaceA x y r
where suc=replace x y h
Q :: a -> Bool Q a = True Q a = False
Theres two main problems i am having. One is I'm not sure what should be the "otherwise" in the leaf function. Another problem is it doesn't show the whole tree just the part after the replacement.
If you think this is complete bull I'll quite happily start over if somebody could give me some insight into what is the best way of tackling this problem is.
Many thanks in advance
spot
spot135
So this is what ive got so far.
data Tree a = Empty | Leaf a | Branch a [Tree a]
[Homework mode on, i.e. hints and careful nudges to help you work it out on your own] The definition above gives two ways to build a Tree with only one data element. Can you see which ones? Is this a good thing? What is the difference between your definition and data Tree a = Empty | Branch a [Tree a] What would the consequences be if you replaced your definition with this one? -k -- If I haven't seen further, it is by standing in the footprints of giants
Ketil Malde
data Tree a = Empty | Branch a [Tree a]
What would the consequences be if you replaced your definition with this one?
And, for extra credit, can you identify similar issues with this definition? Can you improve on it? -k -- If I haven't seen further, it is by standing in the footprints of giants
participants (6)
-
Casey Hawthorne -
Daniel Fischer -
Ketil Malde -
Luke Palmer -
spot135 -
Stefan Holdermans