Filter csv rows with multiple conditions

Question

Hi I want to filter out rows whose 2nd column (Hex) has value 80 or 81 and filter out rows whose 2nd column is 0 only if its below the row which has 81 in the second column:

sample.csv :

Delta,Hex,Type,Time

0,81,DTE,10 pm
1,0,DTE,10 pm
0,01,DTE,10 pm
1,1c,DTE,9 pm
1,0,DTE,10 pm
0,1d,DTE,10 pm
1,0,DTE,10 pm

So here's the script which I wrote which filters out rows with values 80 81 and 0 in the second column(Hex).

Script.py:

import csv

with open('sample.csv', 'r') as f:

  rows=csv.DictReader(f, fieldnames=None,restkey=None,restval=None,dialect='excel',delimiter=",")

  filtered_rows=filter(lambda p:'80' != p['Hex'] and '81' != p['Hex'] and '0' != p['Hex'], rows)

  for i in filtered_rows :

    print (i['Hex'])

So it filters out all the rows which has 0 in their second column.

Current output with the above script:

01
1c
1d

But I dont want to filter the row which has 0 in the second column if its not below the row which has 81 in the second column:

Expected output :

xecgr · Accepted Answer · 2014-10-03 12:29:04Z

1

If you need a non-current state, the 0 condition, you should filter the list iterating it, not with lambda

>>> import csv
>>> with open('sample.csv', 'r') as f:
...     rows=csv.DictReader(f, fieldnames=None,restkey=None,restval=None,dialect='excel',delimiter=",")
...     filtered_rows=[]
...     previous_flag=False
...     for item in rows:
...         if item['Hex'] not in ['81','80'] and not (previous_flag and  item['Hex'] == '0'):
...             filtered_rows.append(item)
...         previous_flag = item['Hex'] == '81'
...     for i in filtered_rows :
...         print (i['Hex'])
... 
01
1c
0
1d
0

edited Oct 3, 2014 at 12:29

answered Oct 3, 2014 at 7:28

xecgr

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2 Comments

RBH Over a year ago

This script will work only if 81 occurs every time after 0 but that's not the case. If 6th row is 0,1d,DTE,10 pm it will not append the 5th row which it should.

xecgr Over a year ago

could you edit your question with new data and the desired result?

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