# Re: Extracting unique values in an array (integer) ?

From: Mary Haley <haley_at_nyahnyahspammersnyahnyah>
Date: Wed, 5 Mar 2008 03:16:17 -0700 (MST)

Hi Christian,

I didn't read your email closely enough, and you did explain what
you meant the first time. My apologies.

I don't think we have a function to do what you're asking. The
one way I thought of is a bit kludgy:

years = (/1991,1990,1991,1990,1990,1990,1991,1991/)
qsort(years)
ny = dimsizes(years)
nuy = num((years(1:)-years(0:ny-2)).ne.0) + 1
print("Number of unique years = " + nuy)

This may be a function worth "officially" adding to NCL, via a built-in
function, rather than one written in NCL.

--Mary

On Wed, 5 Mar 2008, [ISO-8859-1] Christian Pagé wrote:

> Hi Mary,
>
> I think I didn't explain correctly what I want to achieve.
>
> Let a vector of time (udunits in hours since), with daily data.
> I convert it to year, month, day, etc arrays using ut_calendar.
> I would like to know how many years I have... but I cannot use the dimension
> of years since I will have 365/366 values of each year for complete years,
> and less than that for incomplete years.
>
> Example :
> I have these two vectors with the same dimensions, years and months as
> follows.
> years = 1990 1990 1990 1990 1991 1991 1991 1991
> month = 09 10 11 12 01 02 03 04
>
> I want to know how many unique years I have in the years vector, which would
> be equal to 2 in that example.
> It would be the same functionality as the sort -u | wc -l command in
> unix.
>
> Many thanks
>
> Christian
>
> 2008/3/5, Mary Haley <haley_at_ucar.edu>:
>>
>> Hi Christian,
>>
>> I have a weird connection at the moment and can't get to our web
>> pages, but I believe what you want is a function Dennis wrote called
>> generate_unique_indices.
>>
>> See:
>>
>>
>>
>> http://www.ncl.ucar.edu/Document/Functions/Contributed/generate_unique_indices.shtml
>>
>>
>> --Mary
>>
>>
>>
>>
>> On Tue, 4 Mar 2008, [ISO-8859-1] Christian Pagé wrote:
>>
>>> Hi everyone,
>>>
>>> I searched without success...
>>> I was wondering if there already exists a function in NCL to extract
>> unique
>>> values in an integer array ?
>>>
>>> Many thanks,
>>>
>>> --
>>> Christian Pagé
>>>
>

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Received on Wed Mar 05 2008 - 03:16:17 MST

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