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making a checkerboard array? [message #55935]

Tue, 25 September 2007 09:27

Mike[2] is currently offline

Mike[2]
Messages: 99
Registered: December 2005

Member

I'm trying to make a checkerboard mask for an array, but I'm missing
something that is likely to be obvious to the IDL array masters. The
following code makes a pattern like this (use a fixed width font):

+++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++

Can anyone help me fill in the missing rectangles like this?

+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
+++++00000+++++00000+++++00000
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++
00000+++++00000+++++00000+++++

Nx=300
Ny=200
Nrects = 10
Xside = Nx/Nrects
Yside = Ny/Nrects
xs = [replicate(1,Xside), replicate(0,Xside)]
while n_elements(xs) lt Nx do xs = [xs, [replicate(1,Xside),
replicate(0,Xside)]]
xs = xs[0:Nx-1]
ys = [replicate(1,Yside), replicate(0,Yside)]
while n_elements(ys) lt Ny do ys = [ys, [replicate(1,Yside),
replicate(0,Yside)]]
ys = ys[0:Ny-1]
window, xsize=Nx, ysize=Ny
tvscl, xs # ys

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Re: making a checkerboard array? [message #55984 is a reply to message #55935]

Wed, 26 September 2007 10:39

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

JD Smith writes:

> In case that wasn't clear, here it is dfanning style ;)
>
> theRamp = LINDGEN( theNumberofXPixels , theNumberofYPixels )
> theCheckerBoardHorizontalPeriod = 2 * theCheckWidth
> theHorizontalRamp = theRamp MOD theCheckerBoardHorizontalPeriod
> theHorizontalBands = theHorizontalRamp LT theCheckWidth
>
> theRowNumbers = theRamp/theNumberofXPixels
> theCheckerBoardVerticalPeriod = 2 * theCheckHeight
> theVerticalRamp = theRowNumbers MOD theCheckerBoardVerticalPeriod
> theVerticalBands = theVerticalRamp GE theCheckHeight
>
> theCheckerBoard = theHorizontalBands XOR theVerticalBands

Oh, hell. I think I'm going back to all lowercase. :-(

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #55985 is a reply to message #55935]

Wed, 26 September 2007 10:27

JD Smith is currently offline

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Tue, 25 Sep 2007 15:52:33 -0600, David Fanning wrote:

> JD Smith writes:
>
>>> I'm trying to make a checkerboard mask for an array, but I'm missing
>>> something that is likely to be obvious to the IDL array masters.
>>
>> l=lindgen(nx,ny)
>> l=(l mod (xside*2) lt xside) XOR (l/nx mod (yside*2) ge yside)
>
> Well, uh, it's not obvious to me. :-(

Well, l mod (xside*2) produces a horizontal ramp from 0... xside*2,
repeating over and over, the same for each row (as long as the array
width is an even multiple of xside). Comparing this ramp to xside,
ala (ramp lt xside) produces alternating vertical bars of width xside.
Similarly for l/nx (the row number), producing alternating horizontal
bars of height yside. Put them on top of each other and you have a
lovely quilt pattern. But we don't want a quilt, we want a
checkerboard, i.e. we want only those spots where the two bar patterns
don't overlap, hence the exclusive or (XOR).

In case that wasn't clear, here it is dfanning style ;)

theRamp = LINDGEN( theNumberofXPixels , theNumberofYPixels )
theCheckerBoardHorizontalPeriod = 2 * theCheckWidth
theHorizontalRamp = theRamp MOD theCheckerBoardHorizontalPeriod
theHorizontalBands = theHorizontalRamp LT theCheckWidth

theRowNumbers = theRamp/theNumberofXPixels
theCheckerBoardVerticalPeriod = 2 * theCheckHeight
theVerticalRamp = theRowNumbers MOD theCheckerBoardVerticalPeriod
theVerticalBands = theVerticalRamp GE theCheckHeight

theCheckerBoard = theHorizontalBands XOR theVerticalBands

JD

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Re: making a checkerboard array? [message #55986 is a reply to message #55935]

Wed, 26 September 2007 10:29

James Kuyper is currently offline

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

Allan Whiteford wrote:
> Bruce Bowler wrote:
>>> http://www.nerdtests.com/ft_nq.php ;-)
>>
>>
>> Arghhhhhh 91. I didn't think I was *that* nerdy :-)
>>
>
> The test is scoring people too highly... I don't deserve the 94 I got.
> Maybe a few years ago, but not now... surely not now!?!

I got a 97. That seems a bit high, but I'm not inclined to dispute it.

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Re: making a checkerboard array? [message #55993 is a reply to message #55935]

Wed, 26 September 2007 09:44

R.G.Stockwell is currently offline

R.G.Stockwell
Messages: 163
Registered: October 2004

Senior Member

"Bruce Bowler" <bbowler@bigelow.org> wrote in message
news:pan.2007.09.26.15.19.33@bigelow.org...
>> http://www.nerdtests.com/ft_nq.php ;-)
>
> Arghhhhhh 91. I didn't think I was *that* nerdy :-)

OHOH!

{takes test results, prints them to printer, and burns them! Pleasantly
dreams of
scoring only 91}

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Re: making a checkerboard array? [message #55994 is a reply to message #55935]

Wed, 26 September 2007 09:37

Allan Whiteford is currently offline

Allan Whiteford
Messages: 117
Registered: June 2006

Senior Member

Bruce Bowler wrote:
>> http://www.nerdtests.com/ft_nq.php ;-)
>
>
> Arghhhhhh 91. I didn't think I was *that* nerdy :-)
>

The test is scoring people too highly... I don't deserve the 94 I got.
Maybe a few years ago, but not now... surely not now!?!

Maybe it's just English majors bringing the average down ;).

I could tell I was heading for a high score when there wasn't an option
to pick "None of the above, it should be a lower case 'c'" which is what
I really wanted to answer.

Thanks,

Allan

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Re: making a checkerboard array? [message #55999 is a reply to message #55935]

Wed, 26 September 2007 08:29

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Bruce Bowler writes:

> Arghhhhhh 91. I didn't think I was *that* nerdy :-)

Let's just say in college I was an English major and
let it go at that. :-(

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #56000 is a reply to message #55935]

Wed, 26 September 2007 08:28

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Bruce Bowler writes:

> Arghhhhhh 91. I didn't think I was *that* nerdy :-)

Are you available for some map documentation translation work?

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #56001 is a reply to message #55935]

Wed, 26 September 2007 08:19

Bruce Bowler is currently offline

Bruce Bowler
Messages: 128
Registered: September 1998

Senior Member

> http://www.nerdtests.com/ft_nq.php ;-)

Arghhhhhh 91. I didn't think I was *that* nerdy :-)

--
+-------------------+--------------------------------------- ------------+
Bruce Bowler | Those who cast the votes decide nothing. Those who
1.207.633.9600 | count the votes decide everything. - Anon
bbowler@bigelow.org |
+-------------------+--------------------------------------- ------------+

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Re: making a checkerboard array? [message #56003 is a reply to message #55935]

Wed, 26 September 2007 08:02

Mike[2] is currently offline

Mike[2]
Messages: 99
Registered: December 2005

Member

On Sep 25, 12:56 pm, David Fanning <n...@dfanning.com> wrote:

> Are you working through Gonzales and Woods? My 3rd Edition just
> arrived yesterday! :-)

No - I'm making an image fuser that might work better than alpha
blending for pairs of PET images. Your solution almost works. If I
congrid it to make the squares bigger, it is just right. But JD's
is ... well ... I have no idea how a mind just pops that out!

Mike

P.S. Someone who is happy to get his new image processing book may
appreciate the quiz that is going around the lab here:
http://www.nerdtests.com/ft_nq.php ;-)

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Re: making a checkerboard array? [message #56006 is a reply to message #55935]

Wed, 26 September 2007 07:46

Mike[2] is currently offline

Mike[2]
Messages: 99
Registered: December 2005

Member

On Sep 25, 5:34 pm, JD Smith <jdsm...@as.arizona.edu> wrote:
>
> l=lindgen(nx,ny)
> l=(l mod (xside*2) lt xside) XOR (l/nx mod (yside*2) ge yside)

I'm speachless - thanks!

Mike

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Re: making a checkerboard array? [message #56020 is a reply to message #55935]

Tue, 25 September 2007 15:59

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Jean H writes:

> IDL> nx=20
> IDL> ny=20
> IDL> l=lindgen(nx,ny)
> IDL> l=(l mod (nx*2) lt nx) XOR (l/nx mod (ny*2) ge ny)
> IDL> print,l

If there is a question in there, I think this is the answer:

IDL> nx=20
IDL> ny=20
IDL> l =lindgen(nx, ny)
IDL> l=(l mod (2) lt 1) XOR (l/nx mod (2) ge 1)
IDL> print, l
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
1 0
0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 1

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #56021 is a reply to message #55935]

Tue, 25 September 2007 15:07

Jean H. is currently offline

Jean H.
Messages: 472
Registered: July 2006

Senior Member

David Fanning wrote:
> JD Smith writes:
>
>
>>> I'm trying to make a checkerboard mask for an array, but I'm missing
>>> something that is likely to be obvious to the IDL array masters.
>>
>> l=lindgen(nx,ny)
>> l=(l mod (xside*2) lt xside) XOR (l/nx mod (yside*2) ge yside)
>
>
> Well, uh, it's not obvious to me. :-(
>
> Cheers,
>
> David
IDL> nx=20
IDL> ny=20
IDL> l=lindgen(nx,ny)
IDL> l=(l mod (nx*2) lt nx) XOR (l/nx mod (ny*2) ge ny)
IDL> print,l
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0

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Re: making a checkerboard array? [message #56022 is a reply to message #55935]

Tue, 25 September 2007 14:52

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

JD Smith writes:

>> I'm trying to make a checkerboard mask for an array, but I'm missing
>> something that is likely to be obvious to the IDL array masters.
>
> l=lindgen(nx,ny)
> l=(l mod (xside*2) lt xside) XOR (l/nx mod (yside*2) ge yside)

Well, uh, it's not obvious to me. :-(

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #56023 is a reply to message #55935]

Tue, 25 September 2007 14:34

JD Smith is currently offline

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Tue, 25 Sep 2007 09:27:17 -0700, Mike wrote:

> I'm trying to make a checkerboard mask for an array, but I'm missing
> something that is likely to be obvious to the IDL array masters.

> Can anyone help me fill in the missing rectangles like this?
>
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> +++++00000+++++00000+++++00000
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++
> 00000+++++00000+++++00000+++++

l=lindgen(nx,ny)
l=(l mod (xside*2) lt xside) XOR (l/nx mod (yside*2) ge yside)

JD

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Re: making a checkerboard array? [message #56033 is a reply to message #55935]

Tue, 25 September 2007 09:56

David Fanning is currently offline

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Mike writes:

> I'm trying to make a checkerboard mask for an array, but I'm missing
> something that is likely to be obvious to the IDL array masters. The
> following code makes a pattern like this (use a fixed width font):

Here is my implementation:

Function Checkerboard, xsize, ysize, white, black

IF N_Elements(xsize) EQ 0 THEN xsize = 512
IF N_Elements(ysize) EQ 0 THEN ysize = 512
IF N_Elements(white) EQ 0 THEN white = 255
IF N_Elements(black) EQ 0 THEN black = 0

IF xsize MOD 2 NE 0 THEN $
Message, 'The X size must be an even number.'
IF ysize MOD 2 NE 0 THEN $
Message, 'The Y size must be an even number.'

horizontalBoard = FltArr(xsize, ysize)
verticalboard = FltArr(xsize, ysize)
xhalfSize = xsize / 2
x = IndGen(xhalfSize) * 2
yhalfSize = ysize / 2
y = IndGen(yhalfsize) * 2

horizontalBoard[x,*] = 1
verticalBoard[*,y] = 1
verticalBoard = Temporary(verticalBoard) + horizontalBoard
verticalBoard[Where(verticalBoard EQ 2)] = 0
board = FltArr(xsize, ysize) + white
board[Where(verticalBoard GT 0)] = black
RETURN, board
END

Are you working through Gonzales and Woods? My 3rd Edition just
arrived yesterday! :-)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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Re: making a checkerboard array? [message #56071 is a reply to message #55993]

Thu, 27 September 2007 07:54

edward.s.meinel@aero. is currently offline

edward.s.meinel@aero.
Messages: 52
Registered: February 2005

Member

On Sep 26, 12:44 pm, "R.G. Stockwell" <noem...@please.com> wrote:
> "Bruce Bowler" <bbow...@bigelow.org> wrote in message
>
> news:pan.2007.09.26.15.19.33@bigelow.org...
>
>>> http://www.nerdtests.com/ft_nq.php;-)
>
>> Arghhhhhh 91. I didn't think I was *that* nerdy :-)
>
> OHOH!
>
> {takes test results, prints them to printer, and burns them! Pleasantly
> dreams of
> scoring only 91}

99! No, that doesn't mean 'factorial'... Oooo, Agent 99, yowza!

Bruce, why are you so surprised? You're posting on comp.lang.idl-
pvwave, for crying out loud!

Ed "supreme nerd god" Meinel

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