Here's a slight variation of the core concept in the accepted answer to the question Have csv.reader tell when it is on the last line applied to your variation of the problem. Since each row is potentially a different length, there's really no way around having to read the whole file.
import csv
def get_last_row(csv_filename):
with open(csv_filename, 'r') as f:
lastrow = None
for lastrow in csv.reader(f): pass
return lastrow
Update
Here's a simpler and likely faster way to do it using a collections.deque
. I got the idea from one of the answers to the question How to read an output line containing a list of integers produced.
from collections import deque
import csv
def get_last_row(csv_filename):
with open(csv_filename, 'r') as f:
try:
lastrow = deque(csv.reader(f), 1)[0]
except IndexError: # empty file
lastrow = None
return lastrow