问题
I've been Googling and reading this site, and I know folks say that, in general, if you're iterating over a Dataframe, you're likely doing it wrong. So, I figure I'm doing it wrong. The challenge I'm presented with is that I need to make decisions on what to keep versus what to discard based on logic. Best explained with an example. Say my Dataframe looks like:
SO_NUMBER ITEM # SALES_QTY PO_NUMBER PO_QTY PO_PRICE ENOUGH_TO_FILL
--------------------------------------------------------------------------
123 ABC123 5 555 1000 8.88 TRUE
312 ABC123 10 555 1000 8.88 TRUE
123 ABC123 5 777 500 1.11 TRUE
312 ABC123 10 777 500 1.11 TRUE
My Dataframe was constructed by merging my Sales Date with my Purchasing Data. The challenge I'm faced with is making sure that I record the MAXIMUM PO_PRICE for every Sales Order, without exceeding the total PO Quantity. So, for the above data, my result would be, since I had enough to fill:
SO # ITEM # SALES_QTY PO_NUMBER PO_QTY PO_PRICE
----------------------------------------------------------
123 ABC123 5 555 1000 8.88
312 ABC123 10 555 1000 8.88
But, I'm screwed in the following scenario:
SO_NUMBER ITEM # SALES_QTY PO_NUMBER PO_QTY PO_PRICE ENOUGH_TO_FILL
--------------------------------------------------------------------------
123 ABC123 1500 555 1000 8.88 FALSE
312 ABC123 10 555 1000 8.88 TRUE
123 ABC123 5 777 500 1.11 TRUE
312 ABC123 10 777 500 1.11 TRUE
For this scenario, of the 1500 I bought on Row 1, I only have a Total PO Quantity = 1000 for Maximum Price = $8.88. The remaining 500 I'll need to allocate to the lower PO_PRICE. So, I need to perform logic over the dataframe, and, the only way I can think to do it is to iterate over it. In this example, my result set ideally would be:
SO_NUMBER ITEM # SALES_QTY PO_NUMBER PO_QTY PO_PRICE
--------------------------------------------------------------
123 ABC123 1000 555 1000 8.88
123 ABC123 500 555 1000 8.88
312 ABC123 0 555 1000 8.88
123 ABC123 0 777 500 1.11
312 ABC123 0 777 500 1.11
As you can see, the items on the other Sales Orders, I can't report those as being valid, since I can't sell more than I bought, so, those need to get excluded.
I have the logic I wrote and it's fairly convoluted, but I've made great progress. Where I'm getting stuck now is that as I'm iterating over the rows, my logic tells me I need to delete certain rows, and, I don't think it's possible to delete while iterating and still performing the logic checks.
If anyone has any ideas how to help, I would greatly appreciate it. Like I said, I know my approach is wrong, but, I'm too new to Python and I can't think of any other way to do it.
Thanks in advance for any help.
来源：https://stackoverflow.com/questions/64462898/struggling-to-remove-rows-from-my-dataframe