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Re: Removing equal elements from an array [message #49748 is a reply to message #49746]

Wed, 16 August 2006 05:55

Maarten[1]
Messages: 176
Registered: November 2005

Senior Member

Mike wrote:
> Julio wrote:
>> I have an array 'A' with two columns, latitudes and longitudes, and
>> several lines. A need to make another array with the elements of A that
>> don't repeat.
>
> Take a look at the uniq function. Here's an example:

[snip]

Which still doesn't take into account the following situation:

A = [[20.4, 40.3, 50.2, 50.2], $
[30.2, 60.2, 32.4, 32.5]]

in which case no items should be removed. Just thinking out aloud here.
With:
lat = A[*,0] & lon = A[*,1]

we have
idx_lat = uniq(lat) & idx_lon = uniq(lon)

At the very least both index arrays should be the same, if you want to
apply this automagically.

If the precision of the coordinates is limited, you can try to combine
the lat and lon in a single number. If the coordinates are floats, the
following ought to work:

I = lat + (2.0D0^23)*lon
idx = uniq(I)
lat = lat[idx] & lon = lon[idx]

Maarten

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[Message index]

		Re: Removing equal elements from an array By: JD Smith on Wed, 16 August 2006 10:29
		Re: Removing equal elements from an array By: Julio[1] on Wed, 16 August 2006 09:54
		Re: Removing equal elements from an array By: Jean H. on Wed, 16 August 2006 09:12
		Re: Removing equal elements from an array By: Julio[1] on Wed, 16 August 2006 08:24
		Re: Removing equal elements from an array By: Maarten[1] on Wed, 16 August 2006 05:55
		Re: Removing equal elements from an array By: Julio[1] on Wed, 16 August 2006 05:20
		Re: Removing equal elements from an array By: Mike[2] on Tue, 15 August 2006 15:40
		Re: Removing equal elements from an array By: Jean H. on Tue, 15 August 2006 12:14
		Re: Removing equal elements from an array By: Julio[1] on Tue, 15 August 2006 10:36
		Re: Removing equal elements from an array By: Rick Towler on Tue, 15 August 2006 09:30
		Re: Removing equal elements from an array By: JD Smith on Wed, 16 August 2006 10:40

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