#with open('/path/to/file.txt', 'rU') as f:
#    lines = f.readlines()
 
lines = ["blah blah Column1 blah blah",
         "	entry1 val1",
    	 "	entry2 val2",
		 "blah blah Column2 blah blah",
    	 "	entry3 val3",
    	 "	entry4 val4",
    	 ]
 
import re
from collections import defaultdict
d = defaultdict(list)
 
lastKey = None
for line in lines:
	m = re.search('Column\d',line)
	if m: lastKey = m.group()
	else:
		m = re.search('(?<=entry\d ).*',line)
		if m: d[lastKey].append(m.group())
 
print d.items()
 
 

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