| Re: Image thresholding [message #15378] |
Mon, 17 May 1999 00:00 |
David Kastrup
Messages: 33
Registered: February 1998
|
Member |
|
|
davidf@dfanning.com (David Fanning) writes:
> David Brennan (9147261b@clinmed.gla.ac.uk) writes:
>
>> Does anyone know of a fast routine or function for searching through a
>> 3D data set and setting numbers within a predetermined range of values
>> to zero. i.e,
>>
>> the range is 5 - 10
>>
>> A data set contains [0,1,2,3,4,5,6,7,8,9]. It becomes
>> [0,1,2,3,4,0,0,0,0,0]
>>
>> This would save me a lot of time.
>
> a = [0,1,2,3,4,5,6,7,8,9]
> b = a
> b[Where(a ge 5 AND a LT 10)] = 0
> Print, b
> 0,1,2,3,4,0,0,0,0,0
You lose.
If I followup with:
IDL> a=b
IDL> b[Where(a ge 5 AND a LT 10)] = 0
% Attempt to subscript B with <LONG ( -1)> is out of range.
% Execution halted at: $MAIN$
As you can see IDL blows this handy construct if no elements meet the
conditions.
See separate post for correct solution.
--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut f�r Neuroinformatik, Universit�tsstr. 150, 44780 Bochum, Germany
|
|
|
|
| Re: Image thresholding [message #15379 is a reply to message #15378] |
Mon, 17 May 1999 00:00  |
davidf
Messages: 2866
Registered: September 1996
|
Senior Member |
|
|
David Brennan (9147261b@clinmed.gla.ac.uk) writes:
> Does anyone know of a fast routine or function for searching through a
> 3D data set and setting numbers within a predetermined range of values
> to zero. i.e,
>
> the range is 5 - 10
>
> A data set contains [0,1,2,3,4,5,6,7,8,9]. It becomes
> [0,1,2,3,4,0,0,0,0,0]
>
> This would save me a lot of time.
a = [0,1,2,3,4,5,6,7,8,9]
b = a
b[Where(a ge 5 AND a LT 10)] = 0
Print, b
0,1,2,3,4,0,0,0,0,0
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
[Note: This follow-up was e-mailed to the cited author.]
|
|
|
|
| Re: Image thresholding [message #15381 is a reply to message #15378] |
Mon, 17 May 1999 00:00 |
David Kastrup
Messages: 33
Registered: February 1998
|
Member |
|
|
David Brennan <9147261b@clinmed.gla.ac.uk> writes:
> Does anyone know of a fast routine or function for searching through a
> 3D data set and setting numbers within a predetermined range of values
> to zero. i.e,
>
> the range is 5 - 10
>
> A data set contains [0,1,2,3,4,5,6,7,8,9]. It becomes
> [0,1,2,3,4,0,0,0,0,0]
Well, in Matlab you would write
a(find(a >= 5 & a <= 10))=0;
The equivalent in IDL would be
a[where((a ge 5) and (a le 10))] = 0
Only that this fails miserably when no members satify the condition.
A typical case of idiotic semantics of IDL core functions. So we have
to write this as:
w = where((a ge 5) and (a le 10))
if w[0] ge 0 then a[w] = 0
--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut f�r Neuroinformatik, Universit�tsstr. 150, 44780 Bochum, Germany
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
