special iteration through an array

  • Thread starter Thread starter Crirus
  • Start date Start date
C

Crirus

I have a 20x16 array of objects.
I need a way to iterate through the array and only consider few rows and few
columns.

To be clearer, sometimes I need only first 2 rows and last 3 columns to be
considered in loop
Another time, I whould need only first 3 columns and last 4 rows to be
considered...

Anyhow, I will not have separate rows or columns in the same iteration...
So, never something like first 3 rows and last 2 rows... or first 2 columns
and last 3 columns

only rows and columns, at the beginning r at the end.

Any ideea how to implement that?
 
Not totally sure if this is what you want, I have not tested it, just
written in Notepad.

Const xSize As Integer = 20
Const ySize As Integer = 16
Dim Skips( xSize,ySize ) as Boolean
Dim MyObjects(xSize,ySize) as Object
Dim xCount As Integer = 0
Dim yCount As Integer = 0

'Setup All Skips to False
For yCount=0 to yMax-1 Step 1
For xCount=0 to yMax-1 Step1
Skips(xCount,yCount)=False
Next
Next

'Set up rows and cols to skip for example.
Skips(9,3) = Frue

For yCount=0 to ySize-1 Step 1

For xCount=0 to xSize-1 step 1

if Skips(xCount,yCount) Then
'Skip Action
Else
'Do Action
End If

Next
Next


Regards - OHM



















I have a 20x16 array of objects.
I need a way to iterate through the array and only consider few rows
and few columns.

To be clearer, sometimes I need only first 2 rows and last 3 columns
to be considered in loop
Another time, I whould need only first 3 columns and last 4 rows to be
considered...

Anyhow, I will not have separate rows or columns in the same
iteration... So, never something like first 3 rows and last 2 rows...
or first 2 columns and last 3 columns

only rows and columns, at the beginning r at the end.

Any ideea how to implement that?
Click to expand...

Regards - OHM# OneHandedMan{at}BTInternet{dot}com
 
* "Crirus said:
I have a 20x16 array of objects.
I need a way to iterate through the array and only consider few rows and few
columns.

To be clearer, sometimes I need only first 2 rows and last 3 columns to be
considered in loop
Another time, I whould need only first 3 columns and last 4 rows to be
considered...

Anyhow, I will not have separate rows or columns in the same iteration...
So, never something like first 3 rows and last 2 rows... or first 2 columns
and last 3 columns

only rows and columns, at the beginning r at the end.

Any ideea how to implement that?
Click to expand...

Store the indices in 2 arrays and loop through the arrays, get the
values in the 2 index arrays and access the value in the array.
 
Hi Crirus

Just like the others written in this mail and true pseudo my thought about
this
\\\
mySelectedArray as myarrayfunction("R",3,2)
function myarrayfunction (firstIs, rows,columns)
if firstis = "R" then
RowIndexStart = 0
RowIndexEnd = rows
ColIndexStart = coltable.length - (columns + 1)
ColIndexEnd = coltable.length - 1
else
RowIndexStart = rowtable.length - (rows + 1)
RowIndexEnd = rowtable.length - 1
ColIndexStart = 0
ConIndexEnd = columns
end if
///
And then a normal nested for next loop

Cor
 
To help you understand what I need I should tell you that I use that to draw
a bitmap on a control, and when I scroll the image, to redraw only the parts
new exposed...so I whould have to draw some rows and colls depending on
scroll directions
 
Hi Crirus
Still cant see the ideea!
Click to expand...
mySelectedArray as myarrayfunction("R",3,2)
You tell what is the first one the Row or the Column with an R or a whatever
You also tell the amount of rows and the amount of columns
That you do as a function
function myarrayfunction (firstIs, rows,columns)

if firstis = "R" then
' if it is row the startindex = 0 and the end index in this example 3
' the startindex for the columns = 14 and the end index 16
RowIndexStart = 0
RowIndexEnd = rows
ColIndexStart = coltable.length - (columns + 1)
ColIndexEnd = coltable.length - 1
else
RowIndexStart = rowtable.length - (rows + 1)
RowIndexEnd = rowtable.length - 1
ColIndexStart = 0
ConIndexEnd = columns
end if

for i = rowindexStart to rowIndexEnd
for y = colIndexStart to colIndexEnd
add to array
next
next
return array

Not that difficult I thought?

Cor
 
That you did not ask.

:-)
How about first 2 rows and first 3 columns?

--
Click to expand...
But than you need an extra parameter in the same context or something as
FF LF FC and LC and then I would do the test in a select case.

Do you understand it or would i write this in a example?

Cor
 
LOL
I told you there can be any borders, not only first rows and last cols
I can have any borders but not rows only or cols only
 
Cor & Crirus,
The only change I would recommend (to Cor's example) is to make the firstIs
parameter an Enum, either a Flags as I show or FF LF FC and LC as Cor
showed. Either way the Enum will give you intellisense on the allowed
values.

<Flags()> _
Public Enum Position
FirstRow = 0
LastRow = 1 ' Row value is either on (1) or off (0)
FirstColumn = 0
LastColumn = 2 ' Column value is either on (2) or off (0)
End Enum

function myarrayfunction (firstIs As Position, rows,columns)
If (firstIs And Position.LastRow) = Position.FirstRow Then
RowIndexStart = 0
RowIndexEnd = rows
Else
RowIndexStart = rowtable.length - (rows + 1)
RowIndexEnd = rowtable.length - 1
End If

If (firstIs And Position.LastColumn ) = Position.FirstColumnThen
ColIndexStart = 0
ConIndexEnd = columns
Else
ColIndexStart = coltable.length - (columns + 1)
ColIndexEnd = coltable.length - 1
End If

Then when you call it you can use
myarrayfunction (Position.FirstRow Or Position.FirstColumn , x, x)
myarrayfunction (Position.FirstRow Or Position.LastColumn, x, x)
myarrayfunction (Position.LastRow Or Position.FirstColumn , x, x)
myarrayfunction (Position.LastRow Or Position.LastColumn, x, x)

Hope this helps
Jay
 
Whats wrong with my Implementation ?
The skip part is the tricky one here.. I want to implement it as
dinamic as it can be
Click to expand...

Regards - OHM# OneHandedMan{at}BTInternet{dot}com
 
just now I figured out your ideea.. so you first set up the tiles in a
rectangle that I dont need to pick up, then just considering the rest?

I whould like more to minimise the for loops because this is gonna be a
speed optimisation and big loops just make it slower

Beside, I can have that rows and cols at any border.. so first 3 rows and
first 2 cols are my case either
 
I still ned some help.. I'm not used to use flags...

I have 2 values X, Y that shows wich flags should be combined

so X>0 means FirstColumn and Y>0 means FirstRow

How to set does flags into a variable to state both X,Y positive or negative
values?
 
What can be wrong with the followings:
Consider only first if in draw function first

'In a Propery
If Value.X > 0 Then
redraw.direction = Position.FirstColumn
Else
redraw.direction = Position.LastColumn
End If

If Value.Y > 0 Then
redraw.direction = redraw.direction Or Position.FirstRow
Else
redraw.direction = redraw.direction Or Position.LastRow
End If
......
'in a draw function

If redraw.direction = Position.FirstColumn Or Position.FirstRow Then
DrawCroppedMap(redraw.cols, redraw.rows, cols - redraw.cols,
rows - redraw.rows, redraw.cols, redraw.rows)
DrawNewRowsAndCols(0, cols - 1, 0, redraw.rows - 1) 'draw
rows at top
DrawNewRowsAndCols(0, redraw.cols - 1, redraw.rows, rows -
1) 'draw remaining of cols at left
ElseIf redraw.direction = Position.LastColumn Or
Position.LastRow Then
'draw cropped here... not implemented yet IGNORE
DrawNewRowsAndCols(0, cols - 1, 0, redraw.rows - 1) 'draw
rows at top
DrawNewRowsAndCols(cols - 1 - redraw.cols, cols - 1,
redraw.rows, rows - 1) 'draw remaining of cols at right
ElseIf redraw.direction = Position.FirstColumn Or
Position.LastRow Then
'draw cropped here... not implemented yet IGNORE
DrawNewRowsAndCols(0, cols - 1, rows - 1 - redraw.rows,
rows - 1)
DrawNewRowsAndCols(0, redraw.cols - 1, 0, rows - 1 -
redraw.rows)
ElseIf redraw.direction = Position.LastColumn Or
Position.FirstRow Then
'draw cropped here... not implemented yet IGNORE
DrawNewRowsAndCols(0, cols - 1, rows - 1 - redraw.rows,
rows - 1)
DrawNewRowsAndCols(cols - 1 - redraw.cols, cols - 1, 0,
rows - 1 - redraw.rows) 'draw remaining cols at right
End If
........


Private Sub DrawNewRowsAndCols(ByVal xStart As Integer, ByVal xEnd As
Integer, ByVal yStart As Integer, ByVal yEnd As Integer)
For x As Integer = xStart To xEnd
For y As Integer = yStart To yEnd
grBuffer.DrawImage(GetCompleteTile(x, y), New Rectangle(x *
tile.Width, y * tile.Width, tile.Width, tile.Height), New Rectangle(0, 0,
tile.Width, tile.Height), GraphicsUnit.Pixel)
Next
Next
End Sub
Private Sub DrawCroppedMap(ByVal x As Integer, ByVal y As Integer, ByVal
width As Integer, ByVal height As Integer, ByVal newX As Integer, ByVal newY
As Integer)
Dim CropBuff As Bitmap = New Bitmap(bufferMap)
grBuffer.DrawImage(CropBuff, New Rectangle(newX * tile.Width, newY *
tile.Height, width * tile.Width, height * tile.Height), New Rectangle(x *
tile.Width, y * tile.Height, width * tile.Width, height * tile.Height),
GraphicsUnit.Pixel)
End Sub
 
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