Instructor code that was shown on screen

gistfile1.py

import sys

salesTotal = 0
oldKey = None

for line in sys.stdin:
    data = line.strip().split("\t")
    if len(data) != 2:
        # Something has gone wrong. Skip this line.
        continue

    thisKey, thisSale = data
    if oldKey and oldKey != thisKey:
      print oldKey, "\t", salesTotal
      oldKey = thisKey
      salesTotal = 0

     oldKey = thisKey
     salesTotal += float(thisSale)

 if oldKey != None:
   print oldKey, "\t", salesTotal

Hi, I'm very new to this and I was wondering why we need these lines of code at lines 21 and 22.

if oldKey != None: print oldKey, "\t", salesTotal

This is for printing the last line

" oldkey!=None ",means its testing if the oldkey has value or not but since the code has come out of for loop oldkey will have value.
Now if you ask "but we don't need if condition for printing last line".This is where its really interesting, if the (if len(data) != 2) turns out true or moreover if the input data is incorrect then the program wont simply print .

i have implanted the code and as an output i find this
newyork 28
amazon 22
washdc 1
i wander why the tab doesnt work and the number are not in the same line thanks

Can I use groupby function in Pandas? That was my first thought

I think this is probably how the groupby function in pandas works.