Skip to main content

Python blist.sortedlist

The blist package is pretty good. The documentation and care the author has put in is very impressive. It's a shame that it wasn't included in the standard Python distribution, and the reasons given seem to indicate to me that there are not enough people working on large datasets on the Python committee. Any how, I wanted to try out for myself how the sorted list stacks up against a regular python list that is sorted every time after and insertion:


As can be seen, blist.sorted insertion is O(1) and compares quite favorably to the regular Python list.

Timing code follows:

import pylab
from timeit import timeit

l = [1,2,3,4,5,6,7,8,9,10]

def time_things():
  n_loops = 1000
  s = [10, 100, 1000, 10000, 100000]
  blist_time = [timeit("a.add(100)", "import blist; a=blist.sortedlist(range({:d},0,-1))".format(n), number=n_loops)/n_loops for n in s]
  list_time = [timeit("a.append(100); a.sort()", "a=range({:d})".format(n), number=n_loops)/n_loops for n in s]
  return list_time, blist_time

def plot_things(list_time, blist_time):
  s = [10, 100, 1000, 10000, 100000]
  pylab.plot(s, list_time, label='Python list')
  pylab.plot(s, blist_time, label='blist.sortedlist')
  pylab.setp(pylab.gca(), xlabel='List size', ylabel='Time (s)', xscale='log', yscale='log') #, ylim=[1e-9, 1e-3])
  pylab.legend(loc='lower right')

Comments

Popular posts from this blog

A note on Python's __exit__() and errors

Python's context managers are a very neat way of handling code that needs a teardown once you are done. Python objects have do have a destructor method ( __del__ ) called right before the last instance of the object is about to be destroyed. You can do a teardown there. However there is a lot of fine print to the __del__ method. A cleaner way of doing tear-downs is through Python's context manager , manifested as the with keyword. class CrushMe: def __init__(self): self.f = open('test.txt', 'w') def foo(self, a, b): self.f.write(str(a - b)) def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.f.close() return True with CrushMe() as c: c.foo(2, 3) One thing that is important, and that got me just now, is error handling. I made the mistake of ignoring all those 'junk' arguments ( exc_type, exc_val, exc_tb ). I just skimmed the docs and what popped out is that you need to return True or

Using adminer on Mac OS X

adminer is a nice php based sqlite manager. I prefer the firefox plugin "sqlite manager" but it currently has a strange issue with FF5 that basically makes it unworkable, so I was looking for an alternative to tide me over. I really don't want apache running all the time on my computer and don't want people browsing to my computer, so what I needed to do was: Download the adminer php script into /Library/WebServer/Documents/ Change /etc/apache2/httpd.conf to allow running of php scripts (uncomment the line that begins: LoadModule php5_module Start the apache server: sudo apachectl -k start Operate the script by going to localhost Stop the server: sudo apachectl -k stop