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Re: reading an ascii file efficiently [message #68916 is a reply to message #68915]

Fri, 27 November 2009 10:34

b_gom
Messages: 105
Registered: April 2003

Senior Member

Hopefully someone else can provide enlightenment about what technique
will provide the fastest read times for this situation. Since your
text file does not have fixed column widths, you probably can't avoid
using read_ascii\ascii_template or reads.

As for the format codes, you could do this instead if you only care
about the last column:

aux=fltarr(6)
last_val=0.
READS, str, aux, last_val, FORMAT='(6(F0,","),F0)'

On Nov 27, 11:11 am, nata <bernat.puigdomen...@gmail.com> wrote:
> Hi guys,
>
> I'm reading an ascii file and I can do that using different methods.
> Now, I'm trying to use the most efficiently method. I do something
> like this:
>
> lines=FILE_LINES(file)
> rr=STRARR(lines)
> OPENR, lun, file, /GET_LUN
> READF, lun, rr
> FREE_LUN, lun
>
> Now i have all the information in rr variable. Each line have the
> following information:
> 280 , 0 , 280 , 0 , -58.085 , -32.616 , -32.000
> or
> 15 , 1 , 15 , 1 , -60.908 , -32.603 , -32.000
>
> And I need to return only the last value, so -32.000. I can use
> STRSPLIT or STRMID with STRPOS but is not efficient so I'm trying to
> use READS for each line. Something like this:
>
> aux=0.
> result=FLTARR(lines)
> FOR i=0l, lines-1 DO BEGIN
> READS, rr[i], aux, aux, aux, aux, aux, aux, aux,
> FORMAT='(F0,",",F0,",",F0,",",F0,",",F0,",",F0,", ",F0,",",)'
> result[i]=aux
> ENDFOR
>
> You can see that I don't know how to use the FORMAT keyword properly
> so maybe you have an idea of how to skip the first 6 values.
> Using a template, strsplit, etc. I found that this is the most
> efficient way to read this *@#$* file.
>
> Thanks if you can help me with this format or if you have a
> suggestion.
>
> nata

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[Message index]

		Re: reading an ascii file efficiently By: jeanh on Mon, 30 November 2009 06:50
		Re: reading an ascii file efficiently By: natha on Mon, 30 November 2009 06:39
		Re: reading an ascii file efficiently By: David Fanning on Sat, 28 November 2009 11:00
		Re: reading an ascii file efficiently By: penteado on Fri, 27 November 2009 21:04
		Re: reading an ascii file efficiently By: David Fanning on Fri, 27 November 2009 20:56
		Re: reading an ascii file efficiently By: penteado on Fri, 27 November 2009 19:58
		Re: reading an ascii file efficiently By: Heinz Stege on Fri, 27 November 2009 19:27
		Re: reading an ascii file efficiently By: Heinz Stege on Fri, 27 November 2009 19:16
		Re: reading an ascii file efficiently By: penteado on Fri, 27 November 2009 14:45
		Re: reading an ascii file efficiently By: natha on Fri, 27 November 2009 11:02
		Re: reading an ascii file efficiently By: jeanh on Fri, 27 November 2009 10:39
		Re: reading an ascii file efficiently By: b_gom on Fri, 27 November 2009 10:34

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