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Sort without loops [message #45166]

Wed, 17 August 2005 02:08

Ian Dean
Messages: 26
Registered: January 2000

Junior Member

Hi All,
I have a large string array (~100000 elements) that need sorting on two
fields within each string.

e.g. array=['F;100', 'ABC;6', 'DE;2', 'DE;10', 'DE;1']

Order required is a) sort items to left of ';' followed by b) sort items
numerically to right of ';'
This would produce:
ABC;6 DE;1 DE;2 DE;10 F;100

A simple sort (sort(array)) procudes:
ABC;6 DE;1 DE;10 DE;2 F;100

The only way I've found is to conmvert the RH part to I4.4 format within a
loop and search on the new values:
......
for j=0, n_elements(array)-1 do begin
parts=strsplit(array[j], ';', /extract)
RH=string(fix(parts[1]), format='(I4.4)')
new[j]=parts[0]+RH
endfor
order=sort(new)
...
i.e
new array is F;0100 ABC;0006 DE;0002 DE;0010 DE;0001
which is then sorted correctly.

Is there a clever way of sorting on two fields like this without using a
loop. The above algorithm is faaaar slower than just using sort.

I hope I have made this as clear as mud.#

In expectation,
Ian

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[Message index]

		Sort without loops By: Ian Dean on Wed, 17 August 2005 02:08
		Re: Sort without loops By: David Fanning on Fri, 19 August 2005 08:05
		Re: Sort without loops By: MarioIncandenza on Fri, 19 August 2005 07:57
		Re: Sort without loops By: peter.albert@gmx.de on Fri, 19 August 2005 01:01
		Re: Sort without loops By: David Fanning on Thu, 18 August 2005 06:41
		Re: Sort without loops By: Ian Dean on Thu, 18 August 2005 06:28

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