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Date: Tue, 23 Oct 2012 19:30:54 -0500
From: Tim Chase <python.list@tim.thechases.com>
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To: Virgil Stokes <vs@it.uu.se>
Subject: Re: Fast forward-backward (write-read)
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Xref: csiph.com comp.lang.python:31981

On 10/23/12 13:37, Virgil Stokes wrote:
> Yes, I do wish to inverse the order,  but the "forward in time"
> file will be in binary.

Your original post said:

> The data (t_k,y(t_k)), k = 0,1,...,N are stored in ASCII format

making it hard to know what sort of data is in this file.

So I guess it would help to have some sample data to work with, even
if it's just some dummy data and a raw processing loop without doing
anything inside it.  Something like the output of either of these

  $ xxd forward_data.txt | head -50 > forward_head.txt
  $ od forward_data.txt | head -50 > forward_head.txt

plus a basic loop to show how you're extracting the values:

  for line in file("forward_head.txt"):
    data1, data2, data3 = process(line)

and how you want to reverse over them:

  for line in file("reversed.txt"):
    if same_processing_as_forward_source:
      data1, data2, data3 = process(line)
    else:
      data1, data2, data3 = other_process(line)

or do you want something more like

  for line in super_reverse_magic(file("forward_head.txt")):
    data1, data2, data3 = process(line)

?

-tkc