[Tutor] Comparing lines in two files, writing result into a third file

stuart_clemons@us.ibm.com stuart_clemons@us.ibm.com
Wed Apr 23 14:12:09 2003


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Hi Danny:

Thanks for replying.  Let me preface my response by saying I'm basically a 
Python newbie.  I got into Python a little bit about a year ago, but then 
was pulled away to do other things. I'm now being asked to do some things 
where I think Python will be very useful.  So, I'm trying to learn as I 
go, but I gotta produce stuff fairly quickly and I don't have a lot of 
spare time to spend on my learning curve.  I do like Python though, and 
I'm glad I have something to use it for. 

So, anyway, now that I think about it a little bit, perhaps sorted order 
doesn't really matter.  One responder suggested that I use dictionaries in 
my code structure.  My understanding is that dictionaries are mappings, 
not sequences, so I guess ordering is not really relevant here.  FWIW, It 
does turn out that the files I'm working with are always ordered 
sequentially when I get them.

Concerning dictionaries, do you think dictionaries is the structure to use 
? If so, I'll try to spend some time reading up on dictionaries.  I do 
remember having problems reading a file into a dictionary when I tried it 
a year ago or so.

TIA. 
 
- Stuart
 




Danny Yoo <dyoo@hkn.eecs.berkeley.edu>
04/23/2003 01:14 PM
 
        To:     stuart_clemons@us.ibm.com
        cc:     "R. Alan Monroe" <amonroe@columbus.rr.com>, 
<tutor@python.org>
        Subject:        Re: [Tutor] Comparing lines in two files, writing 
result into a third file




On Wed, 23 Apr 2003 stuart_clemons@us.ibm.com wrote:


> Yes, that's the good news !  The input files will always be sorted.

Hi Stuart,


Can you talk a little more about why having the input files sorted is a
good thing?  This is not a silly question, but is meant to help you focus
on a particular part of the problem: there's something about the sorting
that makes this "merging" problem particularly nice.


[By the way, Stuart's problem is similar to the Unix utility 'comm', which
also requires that its inputs are in sorted order.]


Good luck to you!



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<br><font size=2 face="sans-serif">Hi Danny:</font>
<br>
<br><font size=2 face="sans-serif">Thanks for replying. &nbsp;Let me preface
my response by saying I'm basically a Python newbie. &nbsp;I got into Python
a little bit about a year ago, but then was pulled away to do other things.
I'm now being asked to do some things where I think Python will be very
useful. &nbsp;So, I'm trying to learn as I go, but I gotta produce stuff
fairly quickly and I don't have a lot of spare time to spend on my learning
curve. &nbsp;I do like Python though, and I'm glad I have something to
use it for. </font>
<br>
<br><font size=2 face="sans-serif">So, anyway, now that I think about it
a little bit, perhaps sorted order doesn't really matter. &nbsp;One responder
suggested that I use dictionaries in my code structure. &nbsp;My understanding
is that dictionaries are mappings, not sequences, so I guess ordering is
not really relevant here. &nbsp;FWIW, It does turn out that the files I'm
working with are always ordered sequentially when I get them.</font>
<br>
<br><font size=2 face="sans-serif">Concerning dictionaries, do you think
dictionaries is the structure to use ? If so, I'll try to spend some time
reading up on dictionaries. &nbsp;I do remember having problems reading
a file into a dictionary when I tried it a year ago or so.</font>
<br>
<br><font size=2 face="sans-serif">TIA. &nbsp; </font>
<br><font size=2 face="sans-serif">&nbsp;</font>
<br><font size=2 face="sans-serif">- Stuart</font>
<br><font size=2 face="sans-serif">&nbsp;</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>Danny Yoo &lt;dyoo@hkn.eecs.berkeley.edu&gt;</b></font>
<p><font size=1 face="sans-serif">04/23/2003 01:14 PM</font>
<td><font size=1 face="Arial">&nbsp; &nbsp; &nbsp; &nbsp; </font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; To:
&nbsp; &nbsp; &nbsp; &nbsp;stuart_clemons@us.ibm.com</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; cc:
&nbsp; &nbsp; &nbsp; &nbsp;&quot;R. Alan Monroe&quot; &lt;amonroe@columbus.rr.com&gt;,
&lt;tutor@python.org&gt;</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; Subject:
&nbsp; &nbsp; &nbsp; &nbsp;Re: [Tutor] Comparing lines in two files,
writing result into a third file</font></table>
<br>
<br>
<br><font size=2><tt><br>
<br>
On Wed, 23 Apr 2003 stuart_clemons@us.ibm.com wrote:<br>
<br>
<br>
&gt; Yes, that's the good news ! &nbsp;The input files will always be sorted.<br>
<br>
Hi Stuart,<br>
<br>
<br>
Can you talk a little more about why having the input files sorted is a<br>
good thing? &nbsp;This is not a silly question, but is meant to help you
focus<br>
on a particular part of the problem: there's something about the sorting<br>
that makes this &quot;merging&quot; problem particularly nice.<br>
<br>
<br>
[By the way, Stuart's problem is similar to the Unix utility 'comm', which<br>
also requires that its inputs are in sorted order.]<br>
<br>
<br>
Good luck to you!<br>
<br>
</tt></font>
<br>
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