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Re: array [message #90548 is a reply to message #90546]

Mon, 09 March 2015 12:47

Jeremy Bailin
Messages: 618
Registered: April 2008

Senior Member

> Since you're the Value_locate guy, can it be used with 2d arrays? If so, how is monotonic defined in these cases? By using 1d indexes for a 2d array?

Yes, exactly -- it needs to be monotonic with respect to 1D indices.

> And in case of a 2d array, when does one end up with a monotonic 2d array (however this is defined)?

For example:

q = indgen(N1, N2)

gives you an array that is monotonic as far as Value_Locate is concerned. Also, I will sometimes create a 2D array that is monotonic by stacking together individually-monotonic 1D arrays with offsets in the second dimension for the express purpose of using Value_Locate on it. For example, if W is an N1 x N2 array where each W[*,i] is sorted, then you can create a monotonic 2D array is follows:

; in order to make the array monotonic, we need to add an offset to
; each row that will ensure that the minimum value for every subsequent
; row is pushed to being greater than the maximum value of each previous
; row. The following example will technically only work for non-negative W
; and for either integers or not-too-large floats, but can be generalized.
offset = max(W)+1
Wdimen = size(W, /dimen)
; create an N1 x N2 array that adds an appropriate increment to each row
W2 = W + rebin(offset * lindgen(1, Wdimen[1]), Wdimen, /sample)

-Jeremy.

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[Message index]

		array By: 8sushil on Mon, 09 March 2015 02:27
		Re: array By: Helder Marchetto on Mon, 09 March 2015 02:50
		Re: array By: Jeremy Bailin on Mon, 09 March 2015 11:11
		Re: array By: Helder Marchetto on Mon, 09 March 2015 11:53
		Re: array By: Jeremy Bailin on Mon, 09 March 2015 12:47

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