Zaki wrote:
On Jul 17, 2:49 pm, MRAB <pyt...@mrabarnett.plus.com> wrote:
Zaki wrote:
Hey all,
I'm really new to Python and this may seem like a really dumb
question, but basically, I wrote a script to do the following, however
the processing time/memory usage is not what I'd like it to be. Any
suggestions?
Outline:
1. Read tab delim files from a directory, files are of 3 types:
install, update, and q. All 3 types contain ID values that are the
only part of interest.
2. Using set() and set.add(), generate a list of unique IDs from
install and update files.
3. Using the set created in (2), check the q files to see if there are
matches for IDs. Keep all matches, and add any non matches (which only
occur once in the q file) to a queue of lines to be removed from teh q
files.
4. Remove the lines in the q for each file. (I haven't quite written
the code for this, but I was going to implement this using csv.writer
and rewriting all the lines in the file except for the ones in the
removal queue).
Now, I've tried running this and it takes much longer than I'd like. I
was wondering if there might be a better way to do things (I thought
generator expressions might be a good way to attack this problem, as
you could generate the set, and then check to see if there's a match,
and write each line that way).
Why are you checking and removing lines in 2 steps? Why not copy the
matching lines to a new q file and then replace the old file with the
new one (or, maybe, delete the new q file if no lines were removed)?
That's what I've done now.
Here is the final code that I have running. It's very much 'hack' type
code and not at all efficient or optimized and any help in optimizing
it would be greatly appreciated.
import csv
import sys
import os
import time
begin = time.time()
#Check minutes elapsed
def timeElapsed():
current = time.time()
elapsed = current-begin
return round(elapsed/60)
#USAGE: python logcleaner.py <input_dir> <output_dir>
inputdir = sys.argv[1]
outputdir = sys.argv[2]
logfilenames = os.listdir(inputdir)
IDs = set() #IDs from update and install logs
foundOnceInQuery = set()
#foundTwiceInQuery = set()
#IDremovalQ = set() Note: Unnecessary, duplicate of foundOnceInQuery;
Queue of IDs to remove from query logs (IDs found only once in query
logs)
#Generate Filename Queues For Install/Update Logs, Query Logs
iNuQ = []
queryQ = []
for filename in logfilenames:
if filename.startswith("par1.install") or filename.startswith
("par1.update"):
if filename.startswith(("par1.install", "par1.update")):
iNuQ.append(filename)
elif filename.startswith("par1.query"):
queryQ.append(filename)
totalfiles = len(iNuQ) + len(queryQ)
print "Total # of Files to be Processed:" , totalfiles
print "Install/Update Logs to be processed:" , len(iNuQ)
print "Query logs to be processed:" , len(queryQ)
#Process install/update queue to generate list of valid IDs
currentfile = 1
for file in iNuQ:
> print "Processing", currentfile, "install/update log out of", len
> (iNuQ)
> print timeElapsed()
> reader = csv.reader(open(inputdir+file),delimiter = '\t')
> for row in reader:
> IDs.add(row[2])
> currentfile+=1
Best not to call it 'file'; that's a built-in name.
Also you could use 'enumerate', and joining filepaths is safer with
os.path.join().
for currentfile, filename in enumerate(iNuQ, start=1):
print "Processing", currentfile, "install/update log out of", len(iNuQ)
print timeElapsed()
current_path = os.path.join(inputdir, filename)
reader = csv.reader(open(current_path), delimiter = '\t')
for row in reader:
IDs.add(row[2])
print "Finished processing install/update logs"
print "Unique IDs found:" , len(IDs)
print "Total Time Elapsed:", timeElapsed()
currentfile = 1
for file in queryQ:
Similar remarks to above ...
print "Processing", currentfile, "query log out of", len(queryQ)
print timeElapsed()
reader = csv.reader(open(inputdir+file), delimiter = '\t')
outputfile = csv.writer(open(outputdir+file), 'w')
... and also here.
for row in reader:
if row[2] in IDs:
ouputfile.writerow(row)
Should be 'outputfile'.
else:
if row[2] in foundOnceInQuery:
foundOnceInQuery.remove(row[2])
You're removing the ID here ...
outputfile.writerow(row)
#IDremovalQ.remove(row[2])
#foundTwiceInQuery.add(row[2])
else:
foundOnceInQuery.add(row[2])
... and adding it again here!
#IDremovalQ.add(row[2])
currentfile+=1
For safety you should close the files after use.
print "Finished processing query logs and writing new files"
print "# of Query log entries removed:" , len(foundOnceInQuery)
print "Total Time Elapsed:", timeElapsed()
Apart from that, it looks OK.
How big are the q files? If they're not too big and most of the time
you're not removing rows, you could put the output rows into a list and
then create the output file only if rows have been removed, otherwise
just copy the input file, which might be faster.
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