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Code:
I use this method in a mapping project to manipulate m-dimensional
numeric arrays and numeric binary files as if both are (m, n)-dimensional
arrays. I also use a variation of this method to store and retrieve two
positive integer values in a single integer.
An (m, n)-array is simply a matrix with "m" rows down and "n" columns across.
An (m)-array can be substituted by setting it the size of m * n. Then
specific values within the array can be set or retrieved by:
Record number = Row * Array Width + Column
Where:
Row : is "down" in the M-dimension
Array Width: is the number of elements in N-dimension
Column: : is "right" in the N-dimension
If the array is written out to a binary file specific records within
the file can be accessed by:
Record number = Row * (Array Width + 1) * Size of Value + (Column * Size of Value)
Where:
Size of Value: is the number of bytes required to store the value
1: is an alignment into the binary file
This method can be used with binary files written by both (m)- and (m, n)-dimensional
arrays. It can also be used to write to specific locations within the binary file.
To store two values as a single value:
Number = Value1 * Width + Value2
Where:
Value1: is some number
Width: is some known width
Value2: is some number
Width can be:
number of bytes
number of words
number of columns
width of a world
some arbitrary number
To retrieve the two values stored as a single value:
Value1 = Number \ Width
Value2 = Number MOD Width
If you have questions, send me a personal message or start a thread in the support
forum refering to this topic.
Code:
'Date : 4-24-2009
'Author : Walt Decker
'Subject : Single Dimension Numeric Arrays and Numeric Binary Files
'Topic : N-Arrays & Bin Files
'=====================================================================
'Text
' Released to Public Domain by the author.
' I use this method in a mapping project to manipulate m-dimensional
' numeric arrays and numeric binary files as if both are (m, n)-dimensional
' arrays. I also use a variation of this method to store and retrieve two
' positive integer values in a single integer.
' An (m, n)-array is simply a matrix with "m" rows down and "n" columns across.
' An (m)-array can be substituted by setting it the size of m * n. Then
' specific values within the array can be set or retrieved by:
' Record number = Row * Array Width + Column
' Where:
' Row : is "down" in the M-dimension
' Array Width: is the number of elements in N-dimension
' Column: : is "right" in the N-dimension
' If the array is written out to a binary file specific records within
' the file can be accessed by:
' Record number = Row * (Array Width + 1) * Size of Value + (Column * Size of Value)
' Where:
' Size of Value: is the number of bytes required to store the value
' 1: is an alignment into the binary file
' This method can be used with binary files written by both (m)- and (m, n)-dimensional
' arrays. It can also be used to write to specific locations within the binary file.
' To store two values as a single value:
' Number = Value1 * Width + Value2
' Where:
' Value1: is some number
' Width: is some known width
' Value2: is some number
'
' Width can be:
' number of bytes
' number of words
' number of columns
' width of a world
' some arbitrary number
' To retrieve the two values stored as a single value:
' Value1 = Number \ Width
' Value2 = Number MOD Width
'=================================================================================
' If you have questions, send me a personal message or start a thread in the support
' forum refering to this topic.
'=================================================================================
#COMPILE EXE
#BREAK ON
DEFLNG A - Z
FUNCTION PBMAIN () AS LONG
LOCAL Rad AS SINGLE
CONSOLE SET SCREEN 10, 20
CONSOLE SET LOC 200, 300
BmpWide = 72
BmpHigh = 72
WinWide = BmpWide ' width of window
WinHigh = BmpHigh ' height of window
AryWide = BmpWide - 1 ' n-elements in (m, n)-array
AryHigh = BmpHigh - 1 ' m-elements in (m, n)-array
Rad! = (4 * ATN(1)) / 180! ' value of radians for trig functions
Dist = (AryWide \ 2) - 10 ' distance
Cx = AryWide \ 2 ' column center
Cy = AryHigh \ 2 ' row center
DIM Map(AryWide * AryHigh)
MAT Map() = CON(%BLUE) ' make all values blue
'====================================================
' DRAW A CIRCLE IN THE SINGLE DIMENSIONAL ARRAY.
' THIS DATA COULD ALSO BE WRITTEN DIRECTLY TO A
' BINARY FILE
'=====================================================
FOR I = 0 TO 360
X = Cx + Dist * SIN(I * Rad!)
Y = Cy - Dist * COS(I * Rad!)
Rec = Y * AryWide + X 'first equation above
Map(Rec) = %WHITE
NEXT I
GRAPHIC WINDOW "test", 200, 100, BmpWide, BmpHigh TO WinHndl
GRAPHIC ATTACH WinHndl, 0, REDRAW
OPEN "FileTest.Tst" FOR BINARY AS #1 BASE = 0
X = 0
Y = 0
'=====================================================
' DRAW THE CIRCLE IN THE WINDOW AND STORE THE DATA
' IN A BINARY FILE
'=====================================================
FOR I = 0 TO AryHigh
Row = I * AryWide 'first equation
FOR J = 0 TO AryWide
Rec = Row + J 'first equation
GRAPHIC SET PIXEL (X, Y), Map(Rec)
PUT #1, , Map(Rec) 'sequential write
INCR X
NEXT J
INCR Y
X = 0
NEXT I
GRAPHIC REDRAW
CONSOLE SET FOCUS
PRINT "Press a key"
WAITKEY$
'======================================================
' RETRIEVE ONLY THE CIRCLE FROM THE BINARY FILE
'======================================================
FOR I = 0 TO 360
X = Cx + Dist * SIN(I * Rad!)
Y = Cy - Dist * COS(I * Rad!)
Row = Y * (AryWide + 1) * 4 'second equation
Rec = Row + (X * 4) 'second equation
GET #1, Rec, Map(0)
GRAPHIC SET PIXEL (X, Y), Map(0) AND 255 'change display color
NEXT I
GRAPHIC REDRAW
CLOSE #1
KILL "FileTest.Tst"
LOCATE 1, 1
COLOR 4, 7
PRINT "Press a key
WAITKEY$
GRAPHIC WINDOW END
END FUNCTION