python and openpyxl : how to replace new occurence of a date on excel sheet?

Question

I have an excel sheet containing data on two columns (A & B) like that:

A	B	(FYI)
apple	orange	("couple 1")
tomato	carrot	("couple 2")
banana	kiwi	("couple 3")
orange	apple	("couple 1" new occurence)
tomato	carrot	("couple 2" new occurence)
salad	eggplant	("couple 4")

I want to replace every new occurence of a same "couple" by à 0 (zero), like that:

A	B	(FYI)
apple	orange	("couple 1")
tomato	carrot	("couple 2")
banana	kiwi	("couple 3")
0	0
0	0
salad	eggplant	("couple 4")

i taught that a simple code like this one would be ok:

import openpyxl
from openpyxl import *
import numpy
from numpy import *

wb = load_workbook("Desktop/programme/wb.xlsx")

ws = wb["Sheet"]

stop_row = ws.max_row + 1

for n1 in range(1,stop_row) :

    for n2 in range(2,stop_row) :

        item_a = ws.cell(row=n1, column=1).value
        item_b = ws.cell(row=n1, column=2).value

        item_1 = ws.cell(row=n2, column=1).value
        item_2 = ws.cell(row=n2, column=2).value

        if (item_a == item_1 and item_b == item_2) or (item_a == item_2 and item_b == item_1) :

            ws.cell(row=n2, column=1).value = 0
            ws.cell(row=n2, column=2).value = 0

But what i get is:

A	B	(FYI)
apple	orange	("couple 1")
0	0	("couple 2")
0	0	("couple 3")
0	0	("couple 1" new occurence)
0	0	("couple 2" new occurence)
0	0	("couple 4")

any idea why?

Thanks

Answer 1

First iteration, n1 = 1 and n2 = 1. The values item_1 and item_a will be the same with that setup because they're pointing to the same cell. Same thing with item_2 and item_b . Perhaps your second loop should be range(n1 + 1, stop_row) ? Don't worry if n1 + 1 goes larger than stop_row; it just won't count anything instead of looping around.

Also, be aware if you do this, you'll have to start n1 from 0, otherwise the first row will never be considered.