On Fri, 4 Jun 2010 10:15:26 -0700 (PDT)
jjcr...@uw.edu wrote:
> All,
>
> any observations might be helpful. For the display of database contents I
> have the following problem:
>
> Database querys will return data to me in tuples of the following sort:
> each tuple has a unique id, a parent id, and a type.
>
> a parent id of 0 indicates that the element has no parent.
> not all data elements have children
> image elements have no children and must have a parent
>
> So the contents of the db is a tree of sorts:
>
> (1, 0, work)
> (555, 1, image)
> (556, 1, work)
> (557, 556, image)
> (558, 556, work)
> (559, 558, image)
> (560, 558, work)
> (561, 556, image)
> (562, 556, image)
> (563, 1, work)
> (564, 563, work)
> (565, 1, work)
>
> I have a function that will traverse this tree, summoning lists of tuples
> at each leaf. Well and good; it took a lot of trial and error, but it was
> a fine education in tree traversal.
>
> def makeHeirarchy(id):
> id = parentPath(id)[-1]
> rootimages = getImages(id[0])
> rootworks = getWorks(id[0])
> heirarchy = treeTraversal(rootworks, [id, rootimages])
> return heirarchy
>
> ## which calls this recursive function:
>
> def treeTraversal(listIn,result):
> for x in listIn:
> if not getWorks(x[0]):
> result.append(x)
> result.append(getImages(x[0]))
> else:
> result.append(x)
> result.append(getImages(x[0]))
> treeTraversal(getWorks(x[0]), result)
> return result
>
> My problem is that this returns the tuples to me in a flat list.
> I've been trying to work out how I can get it to return some sort of
> nested structure: nested lists, dictionaries, or html thus:
For an indented output, you're simply forgetting to inform the recursive
function aobut current indent level. Example (note: a nested sequence is not a
tree: it has no root):
SPACE , WIDTH, NODE, NL = " " , 4 , "<node>" , '\n'
def indentOutput(s, level=0):
# fake root
if level == 0:
text = NODE
else:
text = ""
# children
level += 1
offset = level * SPACE * WIDTH
for element in s:
if isinstance(element, (tuple,list)):
text += "%s%s%s%s" %(NL,offset,NODE ,
indentOutput(element, level))
else:
text += "%s%s%s" %(NL,offset,element)
return text
s = (1,(2,3),4,(5,(6,7),8),9)
print indentOutput(s)
<node>
1
<node>
2
3
4
<node>
5
<node>
6
7
8
9
Denis
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