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Re: how many array elements with a certain value in a row [message #70270 is a reply to message #70269]

Thu, 01 April 2010 07:14

Chris W
Messages: 12
Registered: May 2007

Junior Member

On Apr 1, 8:56 am, Jeremy Bailin <astroco...@gmail.com> wrote:
> On Apr 1, 9:48 am, Chris W <cwood1...@gmail.com> wrote:
>
>
>
>> On Apr 1, 7:49 am, Jeremy Bailin <astroco...@gmail.com> wrote:
>
>>> Does anyone have a nice simple efficient solution to this problem (I
>>> have a simple inefficient solution and a vague sketch in my mind of a
>>> convoluted but probably efficient solution):
>
>>> I have an image in which many pixels are saturated (=65535, they're
>>> short unsigned). I want to treat each set of consecutive saturated
>>> pixels in a row as a single unit and know how many saturated pixels in
>>> a row there are. So I would like to have a list that contains (a) the
>>> rightmost pixel of each set of consecutive saturated pixels, and (b)
>>> how many saturated pixels there were in the set.
>
>>> Any suggestions?
>
>>> -Jeremy.
>
>> create an array the same size as the image, with values equal to the x
>> index ([0,1,2,3,4,5,.....]:
>
>> x = indgen(512)
>> rx = rebin(x,512,512)
>
>> ;;create a mask
>> mask = image eq 65535
>
>> ;; index values of the mask
>> rxmask = rx*mask
>
>> rightvalues = max(rxmask, dimension=1)
>
>> number_in_rows = total(mask, 1)
>
> No, that won't work - it will only pick up one set per row. There
> could be none or many sets in a ny given row.
>
> -Jeremy.

How about using reform to convert the 2d image into a vector, use
label region to number each set, then histogram with reverse_indices
to find the coordinates of each set (the number in each set will be
the histogram values).

Chris

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[Message index]

		Re: how many array elements with a certain value in a row By: jeanh on Thu, 01 April 2010 08:22
		Re: how many array elements with a certain value in a row By: Jeremy Bailin on Thu, 01 April 2010 08:11
		Re: how many array elements with a certain value in a row By: Chris W on Thu, 01 April 2010 07:14
		Re: how many array elements with a certain value in a row By: Jeremy Bailin on Thu, 01 April 2010 06:56
		Re: how many array elements with a certain value in a row By: Chris W on Thu, 01 April 2010 06:48
		Re: how many array elements with a certain value in a row By: Jeremy Bailin on Thu, 01 April 2010 06:40
		Re: how many array elements with a certain value in a row By: ben.bighair on Thu, 01 April 2010 06:17
		Re: how many array elements with a certain value in a row By: Gray on Thu, 01 April 2010 06:03
		Re: how many array elements with a certain value in a row By: David Fanning on Thu, 01 April 2010 06:02

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