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Date: Sat, 21 Jul 2012 20:40:46 +0100
From: MRAB <python@mrabarnett.plus.com>
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To: python-list@python.org
Subject: Re: My first ever Python program, comments welcome
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On 21/07/2012 20:08, Lipska the Kat wrote:
> Greetings Pythoners
>
> A short while back I posted a message that described a task I had set
> myself. I wanted to implement the following bash shell script in Python
>
> Here's the script
>
> sort -nr $1 | head -${2:-10}
>
> this script takes a filename and an optional number of lines to display
> and sorts the lines in numerical order, printing them to standard out.
> if no optional number of lines are input the script prints 10 lines
>
> Here's the file.
>
> 50	Parrots
> 12	Storage Jars
> 6	Lemon Currys
> 2	Pythons
> 14	Spam Fritters
> 23	Flying Circuses
> 1	Meaning Of Life
> 123	Holy Grails
> 76	Secret Policemans Balls
> 8	Something Completely Differents
> 12	Lives of Brian
> 49	Spatulas
>
>
> ... and here's my very first attempt at a Python program
> I'd be interested to know what you think, you can't hurt my feelings
> just be brutal (but fair). There is very little error checking as you
> can see and I'm sure you can crash the program easily.
> 'Better' implementations most welcome
>
> #! /usr/bin/env python3.2
>
> import fileinput
> from sys import argv
> from operator import itemgetter
>
> l=[]
> t = tuple
What's the purpose of this line?

> filename=argv[1]
> lineCount=10
>
> with fileinput.input(files=(filename)) as f:
> 	for line in f:
> 		t=(line.split('\t'))
> 		t[0]=int(t[0])
> 		l.append(t)
> 	l=sorted(l, key=itemgetter(0))
Short is:

     l.sort(key=itemgetter(0))

>
> 	try:	
> 		inCount = int(argv[2])
> 		lineCount = inCount
You may as well say:

     lineCount = int(argv[2])

> 	except IndexError:
> 		#just catch the error and continue		
> 		None
The do-nothing statement is:

     pass

>
> 	for c in range(lineCount):
> 		t=l[c]
If there are fewer than 'lineCount' lines, this will raise IndexError.
You could do this instead:

     for t in l[ : lineCount]:

> 		print(t[0], t[1], sep='\t', end='')
>