[Tutor] compare and arrange file

[Emile van Sebille]

On 7/12/2011 4:01 PM Edgar Almonte said...
> On Tue, Jul 12, 2011 at 5:44 AM, Peter Otten<__peter__ at web.de>  wrote:
<snip>
>> import csv

imports the comma separated values (csv) file handler utilities module

>>
>> def sortkey(row):
>>     if float(row[1]):
>>         return row[1], True
>>     else:
>>         return row[2], False

... sortkey defines a function that accepts a cvs.reader data row, and 
returns either row[1] and True or row[2] and False based on which of 
row[1] and row[2] has a non-zero value

>>
>> with open("infile.txt", "rb") as instream:
>>     rows = sorted(csv.reader(instream, delimiter="|"), key=sortkey)

rows becomes the sortkey sorted result of the lines of infile.txt

>>
>> with open("outfile.txt", "wb") as outstream:
>>     csv.writer(outstream, delimiter="|").writerows(rows)

... and this writes those results to outfile.txt

you might also try the shortened:

from csv import reader,writer

def sortkey(row): return max(row[1],row[2]),row[1]>row[2]

writer(open("outfile.txt", "wb"), delimiter="|").writerows( 
sorted(reader(open("infile.txt", "rb"), delimiter="|"),key=sortkey))


Emile