Python - Searching .csv file with rows from a different .csv file

Question

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I am attempting to read a single row from a csv file and then have it search another csv file.

I have a masterlist.csv that has a single column called empID. It contains thousands of rows of 9 digit numbers. As well I have ids.csv that also contains a single column called number. It contains hundreds of rows. I am attempting to pull a row from the ids.csv do a search on the masterlist.csv and print out whether it has been found. Then it needs to move to the next row in ids.csv until each row in ids.csv has been searched within the masterlist.csv. I thought it would be as simple as this, however it is not throwing any errors nor returning any results.

Using Python 2.7.12 import csv

masterReader = csv.reader(open("masterlist.csv", "rt"), delimiter=",")
idsReader = csv.reader(open("ids.csv", "rt"), delimiter=",")


for number in idsReader:
    for empID in masterReader:
        if number == empID:
            print (" Found in MasterFile")
        else:
            print ("Is Not Found in MasterFile")

Edit: Adding snippet of data used for testing.

see the docs for reeading csv files, it appears that your syntax is wrong: docs.python.org/2/library/csv.html "with open('ids.csv', 'rb') as csvfile:" for example...at least I have had probkems the past when not opening them this way... — Albert Rothman
– Albert Rothman, Commented Sep 13, 2016 at 18:53
Can you provide a snip of the input? I would suspect a .strip() may solve the issue. Also, you can have it print number and empID to ensure you're getting what you think you're getting. — TemporalWolf
– TemporalWolf, Commented Sep 13, 2016 at 18:55
That doesn't look like it is comma separated to me (unless np++ is mangling it for you) — TemporalWolf
– TemporalWolf, Commented Sep 13, 2016 at 19:14

Dinesh Pundkar · Accepted Answer · 2016-09-13 19:37:16Z

Content of master.csv

Content of ids.csv:

Code:

import csv

f1 = file('master.csv', 'r')
f2 = file('ids.csv', 'r')

c1 = csv.reader(f1)
c2 = csv.reader(f2)

idlist = list(c2)
masterlist = list(c1)

for id in idlist[1:]:
    found = False
    #Need to ignore heading thats why masterlist[1:]
    for master in masterlist[1:]:
        if id == master:
            found = True
    if found:
        print "Found in master file"
    else:
        print "Not found in master file"

f1.close()
f2.close()

Output:

C:\Users\dinesh_pundkar\Desktop>python c.py
Found in master file
Not found in master file
Found in master file
Not found in master file
Found in master file

C:\Users\dinesh_pundkar\Desktop>

More shorter version of code without CSV module

with open('master.csv','r') as master:
    with open('ids.csv','r') as id:
        id_list = id.readlines()[1:]
        master_list = master.readlines()[1:]
        for id in id_list:
            if id in master_list:
                print "Found in master file"
            else:
                print "Not found in master file"

Moses Koledoye · Accepted Answer · 2016-09-13 19:15:55Z

You could easily find the numbers that are common to both by using the intersection of sets and the csv.DictReader as your reader object (not sure if the file actually contains a single column):

with open("masterlist.csv") as f1, open("ids.csv") as f2:
    masterReader = csv.DictReader(f1)
    idsReader = csv.DictReader(f2)

    common = set(row['empID'] for row in masterReader) \
           & set(row['number'] for row in idsReader)
    print(common)

Or use a check of list membership to find rows in idsReader that are contained in masterReader:

masterReader = [row['empID'] for row in masterReader]

for row in idsReader:
    if row['number'] in masterReader:
        print (" Found in MasterFile")
    else:
        print ("Is Not Found in MasterFile")

P.S. considering the update to your question, you may not even need the csv module to do this

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