Re: [Pythoncard-users] Multicolumn List Questions...

[Alex T. <al...@tw...>]

Schollnick, Benjamin wrote:

> Now regarding the reset of the selected item on a multicolumn list...
>
>	def gather_data ( self ):
>        current_item    = self.last_picked[0]
>        highlited       = -1
>        for x in xrange(0, len(self.components.MultiColumnList1.items)):
>            if current_item ==
>self.components.MultiColumnList1.items[x][0]:
>                highlited = x
>                break
>                
>        vsoftware = None
>        self.components.MultiColumnList1.items = []
>        self.components.MultiColumnList1.columnHeadings = []
>        headings = []
>
>        vsoftware, structure = self.odbc_database.select_statement (
>fetch="*",
>                                      table=self.database_name,
>orderby=self.orderbys)
>        for x in structure:
>            headings.append ( x[0].replace("_", " ") )
>        self.components.MultiColumnList1.columnHeadings = headings
>
>        data = []
>        line = []
>        for x in vsoftware:
>            for y in x:
>                line.append ( str(y) )
>            data.append ( line )
>            line = []
>
>        self.components.MultiColumnList1.items = data
>        print dir(self.components.MultiColumnList1)
>        self.components.MultiColumnList1.SetFocus ( highlited )
>
>The penalty is too high.....
>
>Here's some background.  The multicolumn list is a representation of
>what data is in a database (accessed via ODBC)...  The gather_data
>function is used to refresh the data in the database view...
>
>After any changes (Editting, Adding, Removing) I need to refresh, but
>the table could be 400+ entries.
>
>  
>
Do you need to re-retrieve the whole table ?
Can you not remember which row you were editing and deal only with that ?
    (I'm naive about DBs - can you tell ?  :-)

>It would be rather annoying for a user to make a change at the end of
>the table, and then have the table refreshed, and have to scroll all the
>way down to the end (again).....
>  
>
>SetSelection works to highlight the text.  But it doesn't change the
>visible portion of the table to be in the viewing area.... 
>
>The verified Software table is only roughly 100+ items, but if I use the
>for loop...
>
>        for x in xrange(0, len(self.components.MultiColumnList1.items)):
>            if current_item ==
>self.components.MultiColumnList1.items[x][0]:
>                highlited = x
>                break
>
>It adds roughly a 1-2 seconds to the load process....
>
>Any suggestions?
>  
>
I'm surprised that the time to load the whole table from the DB, then 
load that whole thing into the multicolumnlist is small enough for the 
extra 1-2 seconds to matter.

But .... it looks to me as though what you're doing in the loop

        for x in xrange(0, len(self.components.MultiColumnList1.items)):
            if current_item == self.components.MultiColumnList1.items[x][0]:
                highlited = x
                break
is getting the row number where the current_item was *before* any edit to the db.

I'd have thought that once you'd edited (or deleted or added), it could be in a different row number - no ?

Can't you remove that loop entirely, and get the line number while loading the table from the DB :

        data = []
        line = []
	highlited = -1
	count = 0
        for x in vsoftware:
            for y in x:
                line.append ( str(y) )
            data.append ( line )
	    if line[0] == current_item: highlighted = count
	    count += 1
            line = []

        self.components.MultiColumnList1.items = data
        print dir(self.components.MultiColumnList1)
        self.components.MultiColumnList1.SetFocus ( highlited )


If you can't use that, then the other possibility is to retrieve the 
entire table, and scan that. This saves a significant overhead for 
accessing each item within the multicolumnlist - but obviously can't be 
done if your table is too large - i.e. 400 x ?? columns
(if it is too large, you may still be able to retrieve the datamap 
dictionary, and access that - but if you can do this it is easier)

What I tried in my copy of the sample/multicolumnlist was

>     def on_which_mouseClick(self, event):
>         #   current_item = "Yes"
>         current_item = "Not to be found"
>         tstart = time.time()
>         highlited = -1
>         for j in range(20):   # 20 time just to make it measurable
>             for x in xrange(0, len(self.components.theList.items)):
>                 if current_item == self.components.theList.items[x][0]:
>                     highlited = x
>                     break
>         print highlited, time.time()-tstart
>
>         tstart = time.time()
>         them = self.components.theList.items
>         highlited = -1
>         for j in range(20):   # 20 time just to make it measurable
>             for x in xrange(0, len(them)):
>                 if current_item == them[x][0]:
>                     highlited = x
>                     break
>         print highlited, time.time()-tstart

and this gave times of ~ 6 seconds for the first loop, versus no 
measurable time for the second.



-- 
Alex Tweedly       http://www.tweedly.net



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