On 21.07.2012 21:08, 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=[]
You can do without this, see below.
t = tuple
This initialization does nothing. Assignment t=(line.split('\t')) makes
`t` a list (not a tuple), discarding any previous value. And you don't
really need t:
with fileinput.input(files=(filename)) as f:
for line in f:
t=(line.split('\t'))
t[0]=int(t[0])
l.append(t)
List comprehension is your friend, and now you don't need to initialize
l to an empty list.
with open(filename) as f:
l = [line.split('\t') for line in f]
The first element of each row is now a string, but it's easy to fix:
l=sorted(l, key=itemgetter(0))
Use in-place sorting and cast the sorting element to int
l.sort(key=lambda t: int(t[0]))
inCount = int(argv[2])
lineCount = inCount
lineCount = int(argv[2]) works just fine
for c in range(lineCount):
t=l[c]
print(t[0], t[1], sep='\t', end='')
Whenever you write "for i in range(n)" you're (probably) doing it wrong.
Here you can use list slicing, and as a bonus the program doesn't bomb
when lineCount is greater than length(l)
for t in l[:lineCount]:
print(t[0], t[1], sep='\t', end='')
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