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Re: Splitting An Array Of Strings Without Using Loops [message #35936 is a reply to message #35881]

Mon, 28 July 2003 16:00

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Mon, 28 Jul 2003 11:24:50 -0700, Rick Towler wrote:

> "Darrick White" wrote...
>
>> It looks like I'm not explaining my problem clearly.
>
>> Is there a way (not knowing what data set input is used) to transform
>> my data into the corresponding result array?
>
> I don't think the issue is one of clarity, but of possibility. Unless
> JD can save you with some magical incarnation of HISTOGRAM you are going
> to have to change your design criteria or use a loop. If performance is
> really that important write this function in C.
>
> -Rick

Come on people. I don't use HISTOGRAM for everything. I use it very
rarely, in fact.

How about something like:

nums=strsplit(strjoin(data,':'),':',/EXTRACT)
cnts=long(total(byte(data) eq 58b,1))+1L

Now you have a list of tuple-counts and the tuples themselves in a long
list. You could (yes) use HISTOGRAM or perhaps many other methods to
stick these into an array as you describe without looping, but rather than
show something you'd forget 5 minutes after dropping it into your code,
I'll join Rick in saying that if parsing these strings quickly is this
important to you, you'll get better results by re-designing the input
format, or pre-parsing them using a language better suited to these
manipulations. And on the off chance that you're suffering from the
"must-optimize-everything-in-sight" disease, you'll want to make sure a
readable and straightforward input loop won't meet your needs before
venturing too far into IDL esoterica:

b=make_array(/LONG,VALUE=-1,max(cnt),n_elements(data))
for i=0,n_elements(data)-1 do b[0,i]=strsplit(data[i],':',/EXTRACT)

Note that there's no integer (long or otherwise) definition of NaN, so I
used -1.

JD

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[Message index]

		Splitting An Array Of Strings Without Using Loops By: darrick.white on Thu, 24 July 2003 21:42
		Re: Splitting An Array Of Strings Without Using Loops By: Pavel Romashkin on Tue, 29 July 2003 11:10
		Re: Splitting An Array Of Strings Without Using Loops By: JD Smith on Tue, 29 July 2003 09:24
		Re: Splitting An Array Of Strings Without Using Loops By: Pavel Romashkin on Tue, 29 July 2003 08:46
		Re: Splitting An Array Of Strings Without Using Loops By: JD Smith on Mon, 28 July 2003 16:00
		Re: Splitting An Array Of Strings Without Using Loops By: Paul Van Delst[1] on Mon, 28 July 2003 11:47
		Re: Splitting An Array Of Strings Without Using Loops By: Rick Towler on Mon, 28 July 2003 11:24
		Re: Splitting An Array Of Strings Without Using Loops By: David Fanning on Mon, 28 July 2003 10:23
		Re: Splitting An Array Of Strings Without Using Loops By: darrick.white on Mon, 28 July 2003 10:17
		Re: Splitting An Array Of Strings Without Using Loops By: R.Bauer on Sat, 26 July 2003 04:10

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