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Re: how to use wavelet transformation function in IDL? [message #64629 is a reply to message #64624]

Mon, 12 January 2009 09:17

Chris W
Messages: 12
Registered: May 2007

Junior Member

On Jan 12, 10:49 am, Hu <jha...@gmail.com> wrote:
> Hi, there
> I got a time-series data array (suppose array X ), Now I want to use
> wavelet functions in IDL library to filter the array, so that I can
> remove the abnormal data elements and make the time-series data more
> reasonable.
>
> Which functions should I use?
>
> In fact, I check some methods like WV_FN_COIFLET, or WV_DENOISE, but
> it dose not work, and the online help has no examples about this
> parts. So, I will be appreciate if you can give me an example. Many
> thanks.

Here are the steps I have used with the discrete wavelet transform:
(see idl help on wv_dwt)

;;Get information about the chosen wavelet:
;; could use any of the wv_fn_****** functions
info = wv_fn_symlet(12,scaling,wvx, ioff, joff)

nl = 3 ;; depth of the transform
;;Take the wavelet transform:
xdwt = wv_dwt(image, scaling,wvx, ioff, joff , n_levels=nl)

;;operate on xdwt, e.g, to get rid of noise
.......
newdwt = ..........

;; inverse the transform with the inverse keyword
idwt = wv_dwt(newdwt,scaling,wvx,ioff,joff, N_LEVELS=nl, INVERSE=1)

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[Message index]

		Re: how to use wavelet transformation function in IDL? By: jkj on Tue, 13 January 2009 05:25
		Re: how to use wavelet transformation function in IDL? By: Chris W on Mon, 12 January 2009 09:17
		Re: how to use wavelet transformation function in IDL? By: Hu on Thu, 15 January 2009 14:01

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