Slow Nested For Loop Example

nest_loop.py

#data
old_list = [
	{'name': "matthew", 'test_result1': "A", 'test_result2': "A"},
	{'name': "steve", 'test_result1': "B", 'test_result2': "D"},
	{'name': "dave", 'test_result1': "C", 'test_result2': "F"}
]

new_list = [
	{'name': "steve", 'test_result1': "A", 'test_result2': "F"},
	{'name': "matthew", 'test_result1': "B", 'test_result2': "F"},
	{'name': "dave", 'test_result1': "C", 'test_result2': "F"}
]

#this example is slow
for old_row in old_list:
	for new_row in new_list:
		if (new_row['name'] == old_row['name']):
			print "found a match"
			
			
# faster example
old_dict = {old_row['name']: old_row for old_row in old_list}
del old_list

new_dict = {new_row['name']: new_row for new_row in new_list}
del new_list

for new_key, new_row  in new_dict.iteritems():
	if old_dict.get(new_key):
		print "found a match"