Printing Results from Loops - python-2.7

Question

I currently have a piece of code that works in two segments. The first segment opens the existing text file from a specific path on my local drive and then arranges, based on certain indices, into a list of sub list. In the second segment I take the sub-lists I have created and group them on a similar index to simplify them (starts at def merge_subs). I am getting no error code but I am not receiving a result when I try to print the variable answer. Am I not correctly looping the original list of sub-lists? Ultimately I would like to have a variable that contains the final product from these loops so that I may write the contents of it to a new text file. Here is the code I am working with:
from itertools import groupby, chain
from operator import itemgetter
with open ("somepathname") as g:
# reads text from lines and turns them into a list sub-lists
lines = g.readlines()
for line in lines:
matrix = line.split()
JD = matrix [2]
minTime= matrix [5]
maxTime= matrix [7]
newLists = [JD,minTime,maxTime]
L = newLists
def merge_subs(L):
dates = {}
for sub in L:
date = sub[0]
if date not in dates:
dates[date] = []
dates[date].extend(sub[1:])
answer = []
for date in sorted(dates):
answer.append([date] + dates[date])
new code
def openfile(self):
filename = askopenfilename(parent=root)
self.lines = open(filename)
def simplify(self):
g = self.lines.readlines()
for line in g:
matrix = line.split()
JD = matrix[2]
minTime = matrix[5]
maxTime = matrix[7]
self.newLists = [JD, minTime, maxTime]
print(self.newLists)
dates = {}
for sub in self.newLists:
date = sub[0]
if date not in dates:
dates[date] = []
dates[date].extend(sub[1:])
answer = []
for date in sorted(dates):
print(answer.append([date] + dates[date]))
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