How to filter dicts in python, the right way.

filterdict.py

# -*- coding: utf-8 -*-
# <nbformat>3.0</nbformat>

# <rawcell>

# How to filter Python dictionaries, the right way.
# 
# Expected output:
# Original list lookup => 100 loops, best of 3: 9.82 ms per loop
# Dict trick lookup => 1000 loops, best of 3: 315 us per loop
#
# The Pythonic Way => 1000 loops, best of 3: 226 us per loop

# <codecell>

# Original look-up in list
import uuid
default_cols_list = [str(uuid.uuid4()) for _ in range(10 ** 3)]
dummy_data = dict([(item, None) for item in default_cols_list])

print "Original list lookup =>",
%timeit dict([(key, value) for key, value in dummy_data.iteritems() if key in default_cols_list])

# Second try, dict trick
default_cols_dict = dict([(item, 1) for item in default_cols_list])

print "Dict trick lookup =>",
%timeit dict([(key, value) for key, value in dummy_data.iteritems() if key in default_cols_dict])

# The pythonic way:
print "\nThe Pythonic Way =>",
%timeit {key: value for key, value in dummy_data.iteritems() if key in dummy_data}