Looping function

[Charlie Brown]

I am using something like the following function to loop through a
recipe program I am working on. As I was writing it, I starting
thinking this isn't going to work at all... but not I'm not so sure.
Will this code work, or cause me problems?

Private Sub DoSomething()
Dim viCount As Integer = _varianceList.C ount
For i As Integer = 0 To viCount - 1
Dim vi As ProductionVaria nceItem = _varianceList(i )
vi.ProductionOu t = GetProductionOu t(vi, _varianceList)
Next
End Sub

Private Function GetProductionOu t(ByVal item As
ProductionVaria nceItem, ByVal itemList As List(Of
ProductionVaria nceItem)) As Double
Dim itemCount As Integer = itemList.Count
For i As Integer = 0 To itemCount - 1
Dim vi As ProductionVaria nceItem = itemList(i)

'do something

Next
End Function

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Re: Looping function

Charlie Brown wrote:

I am using something like the following function to loop through a
recipe program I am working on. As I was writing it, I starting
thinking this isn't going to work at all... but not I'm not so sure.
Will this code work, or cause me problems?
>
Private Sub DoSomething()
Dim viCount As Integer = _varianceList.C ount
For i As Integer = 0 To viCount - 1
Dim vi As ProductionVaria nceItem = _varianceList(i )
vi.ProductionOu t = GetProductionOu t(vi, _varianceList)
Next
End Sub
>
Private Function GetProductionOu t(ByVal item As
ProductionVaria nceItem, ByVal itemList As List(Of
ProductionVaria nceItem)) As Double
Dim itemCount As Integer = itemList.Count
For i As Integer = 0 To itemCount - 1
Dim vi As ProductionVaria nceItem = itemList(i)
>
'do something
>
Next
End Function

What is it that you are trying to do?

That code would loop all combinations of two items, including of course
combining each item with itself. So, if you have 100 items the "do
something" code will run 10000 times.

--
Göran Andersson
_____

http://www.guffa.com

[Tom Shelton]

Re: Looping function

On 2008-06-13, Charlie Brown <cbrown@duclaw. comwrote:

I am using something like the following function to loop through a
recipe program I am working on. As I was writing it, I starting
thinking this isn't going to work at all... but not I'm not so sure.
Will this code work, or cause me problems?
>
Private Sub DoSomething()
Dim viCount As Integer = _varianceList.C ount
For i As Integer = 0 To viCount - 1
Dim vi As ProductionVaria nceItem = _varianceList(i )
vi.ProductionOu t = GetProductionOu t(vi, _varianceList)
Next
End Sub
>
Private Function GetProductionOu t(ByVal item As
ProductionVaria nceItem, ByVal itemList As List(Of
ProductionVaria nceItem)) As Double
Dim itemCount As Integer = itemList.Count
For i As Integer = 0 To itemCount - 1
Dim vi As ProductionVaria nceItem = itemList(i)
>
'do something
>
Next
End Function

Well... _varianceList appears to be a member variable, so if GetProductionOu t
only works on that list, then it seems pointless to pass it in the arguments
list - since it can directly access it anyway. So, if that's the case (which
is unclear from the context) then I would probably change the signature of
GetProductionOu t to be something like:

Private Function GetProductionOu t (ByVal item As ProductionVaria nceItem) As Double
' do stuff
End Function

As for the looping, it's hard to say. There is nothing technically wrong with
your loops - but, there maybe better ways of doing this. But, it ultimately
depends on what the code is trying to accomplish. The first loop looks to me
that it could be written more clearly as a For Each:

Public Sub DoSomething ()
For Each vi As ProductionVaria nceItem In _varianceList
vi.ProductionOu t = GetProductionOu t(vi)
Next
End Sub

Even if I was going to do a for loop (which is slightly faster then a for
each), then I would most likely write it like this:

Public Sub DoSomething ()
For i As Integer = 0 To _varianceList.C ount - 1
vi.ProductionOu t = GetProductionOu t(_varianceList (i))
Next
End Sub

The same applies to the GetProductionOu t function. Unless you need to use the
final value of i after the loop - then you might as well declare it in the
loop, so that you are reducing the scope of i to it's narowest use.

Anyway, like I said - there doesn't appear to be anything technically wrong
with your loops or any reason to believe that they won't "work"...

--
Tom Shelton

[Tom Shelton]

Re: Looping function

On 2008-06-13, Göran Andersson <guffa@guffa.co mwrote:

Charlie Brown wrote:

>I am using something like the following function to loop through a
>recipe program I am working on. As I was writing it, I starting
>thinking this isn't going to work at all... but not I'm not so sure.
>Will this code work, or cause me problems?
>>
>Private Sub DoSomething()
> Dim viCount As Integer = _varianceList.C ount
> For i As Integer = 0 To viCount - 1
> Dim vi As ProductionVaria nceItem = _varianceList(i )
> vi.ProductionOu t = GetProductionOu t(vi, _varianceList)
> Next
>End Sub
>>
>Private Function GetProductionOu t(ByVal item As
>ProductionVari anceItem, ByVal itemList As List(Of
>ProductionVari anceItem)) As Double
> Dim itemCount As Integer = itemList.Count
> For i As Integer = 0 To itemCount - 1
> Dim vi As ProductionVaria nceItem = itemList(i)
>>
> 'do something
>>
> Next
> End Function

>
What is it that you are trying to do?
>
That code would loop all combinations of two items, including of course
combining each item with itself. So, if you have 100 items the "do
something" code will run 10000 times.
>

Yeah, I didn't even consider the performance implications!

--
Tom Shelton

[=?Utf-8?B?RmFtaWx5IFRyZWUgTWlrZQ==?=]

RE: Looping function

It appears to me that the value of productionOut for each item in the array
depends on the properties of all the objects in the array. Therefore, it
seems to me at least potentially incorrect if later an entry was changed that
would somehow effect the value of an already computed productionOut.

In essence, what I mean is, suppose you compute a value of _varianceList
(5).productionO ut = 7.3. If the computation of _varianceList
(3).productionO ut needed the value of _varianceList(5 ).productionOut , then it
would have (possibly) had a different value. Therefore the computation of
_varianceList(3 ) is in doubt, etc, etc...

I don't know your subject or problem definition to know if this is a problem
or not however...

"Charlie Brown" wrote:

I am using something like the following function to loop through a
recipe program I am working on. As I was writing it, I starting
thinking this isn't going to work at all... but not I'm not so sure.
Will this code work, or cause me problems?
>
Private Sub DoSomething()
Dim viCount As Integer = _varianceList.C ount
For i As Integer = 0 To viCount - 1
Dim vi As ProductionVaria nceItem = _varianceList(i )
vi.ProductionOu t = GetProductionOu t(vi, _varianceList)
Next
End Sub
>
Private Function GetProductionOu t(ByVal item As
ProductionVaria nceItem, ByVal itemList As List(Of
ProductionVaria nceItem)) As Double
Dim itemCount As Integer = itemList.Count
For i As Integer = 0 To itemCount - 1
Dim vi As ProductionVaria nceItem = itemList(i)
>
'do something
>
Next
End Function
>

[Cor Ligthert[MVP]]

Re: Looping function

Tom,

>>
>That code would loop all combinations of two items, including of course
>combining each item with itself. So, if you have 100 items the "do
>something" code will run 10000 times.
>>

>
Yeah, I didn't even consider the performance implications!
>
--

Not about the methods, but about your message.

In my idea is this very short as it is about bitmap processing
I can really not see any performance implications.

Cor

[Cor Ligthert[MVP]]

Re: Looping function

Charlie,

One of those loops is as I see it completely withouth sense.

As I see it right they both do exactly the same

Cor

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Re: Looping function

Cor Ligthert[MVP] wrote:

Charlie,
>
One of those loops is as I see it completely withouth sense.
>
As I see it right they both do exactly the same
>
Cor

No, they don't do the same thing at all. One loop is within the other.

I don't know if that is what's intended (that's why I asked what he's
trying to do), but that's what the code does.

--
Göran Andersson
_____

http://www.guffa.com

[Tom Shelton]

Re: Looping function

On 2008-06-14, Cor Ligthert[MVP] <notmyfirstname @planet.nlwrote :

Tom,

>>>
>>That code would loop all combinations of two items, including of course
>>combining each item with itself. So, if you have 100 items the "do
>>something" code will run 10000 times.
>>>

>>
>Yeah, I didn't even consider the performance implications!
>>
>--

>
Not about the methods, but about your message.
>
In my idea is this very short as it is about bitmap processing
I can really not see any performance implications.
>
Cor

It's the number of times the loop runs, and the question of wether it's
necessary or not. Somethies, Cor, there are better ways to do things that can
improve performance.

--
Tom Shelton

[Cor Ligthert[MVP]]

Re: Looping function

>

No, they don't do the same thing at all. One loop is within the other.
>

Yea, but in my idea is the one inside the other doing the same loop
completely again

Cor

[Charlie Brown]

Re: Looping function

On Jun 14, 1:58 pm, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nl>
wrote:

No, they don't do the same thing at all. One loop is within the other.

>
Yea, but in my idea is the one inside the other doing the same loop
completely again
>
Cor

@Everyone
Thanks for everyone's input.

Yes, it does look a little ridiculous looping through itself, but here
is the situation. I have a list of recipes that have been
"produced" (i.e. made by people each day). Let's say, today the
restaurant has made 32 Qt's of Spicy BBQ Sauce. One of the
ingredients of Spicy BBQ sauce is just plain BBQ Sauce. BBQ sauce is
also in the list because 10 QT's of it were made for other reasons.

So I need to loop through the list and find any items that have
ingredients that are also on the same list and then add the right
amount to them, so I know the total made.

In the end, I used something very similar to what i posted, it seems
to working fine, list total count is about 500 and won't creep to much
higher than that in the foreseeable future.

@Tom Shelton
I use the For... Next instead of For Each for performance sake,
although I agree it's probably not much to worry about. As for the
referencing of the count outside of the loop, that's there for legacy
sake, and will get tossed during the next big iteration when i have
time to replace all of them, for now I like to keep the code
consistent.

@Family Tree Mike
Exactly. You seem to have hit the nail on the head about what the
code does. The biggest problem is that some ingredients are in
mutliple recipes. And those recipes can also be ingredients in other
recipes. There is some pretty deep nesting involved, nearly 4 levels
in some places. This increases the complexity of the loops and does
indeed change the .ProductionOut values quite often in the middle of
the loop.