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Re: filling in missing values [message #67841 is a reply to message #67719]

Wed, 26 August 2009 08:17

Laura
Messages: 9
Registered: August 2009

Junior Member

On Aug 25, 11:50 am, Craig Markwardt <craig.markwa...@gmail.com>
wrote:
> On Aug 25, 8:34 am, Laura <haixia...@gmail.com> wrote:
>
>> Hi, I'm new to IDL and working on data files that assign a particular
>> value for where the data is not available. But I want to replace such
>> values with the nearest valid value in the array. Is there an
>> efficient way to do that instead of loop?
>
> Yes. If you can tolerate always replacing using the good value on the
> left, then this would do the trick.
>
> wh = where(data EQ BAD_VALUE, ct)
> while ct GT 0 do begin
> data[wh] = data[wh-1]
> wh = where(data EQ BAD_VALUE, ct)
> endwhile
>
> It keeps on replacing until no values are left.
>
> But if you are trying to replace bad values with local good values,
> why not use the median function?
>
> medval = median(data, 5) ;; Sliding 5-point median
> wh = where(data EQ BAD_VALUE, ct)
> if ct GT 0 then data[wh] = medval[wh]
>
> There are ways to be smarter about that. For example the median
> includes the bad values, and one may want to filter them out first.
>
> Craig

Thanks a lot! I like the median one better!

--Laura

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[Message index]

		filling in missing values By: Laura on Tue, 25 August 2009 05:34
		Re: filling in missing values By: Laura on Wed, 26 August 2009 08:17
		Re: filling in missing values By: Craig Markwardt on Tue, 25 August 2009 08:50

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