How to create a list in python when the elements contain commas

Question

How do I create a list of strings in python where the strings can contain commas such that the interpreter doesn't break on commas prematurely.

I am reading in a template csv file, created by MSExcel. The contents are 2 columns: col1 = color, col2 = a sentence that can contain a comma. The content is as follows:

Light Green,"Matches type, instance, etc."
Red,Happens in BD10 but not BD20
Blue,"Instance and time matches, type doesn't match"
Yellow,Caught on replay

When I read in and output what was read, it breaks the input line on all commas.

#my code snippet, please excuse any typos during sanitization
with open('outfile.csv','r') as infile:
   blah = infile.readlines()
   for i in blah:
      line = i.strip().split(",")
      print line

My output:
['Light Green', '"Matches type', ' instance', ' etc."']
['Red', 'Happens in BD10 but not BD20']
['Blue', '"Instance and time matches', ' type doesn\'t match"']
['Yellow', 'Caught on replay']

How do I tell python to ignore commas when it's within "" and break at commas all other times?

score 4 · Answer 1 · answered Sep 09 '15 at 23:48

4

python provides tools to parse csv files ... you should use them

print list(csv.reader(open("outfile.csv","r")))

maybe?

answered Sep 09 '15 at 23:48

Joran Beasley

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dawg · Answer 2 · 2015-09-10T00:29:11.810

The cvs module makes this easy as pie.

Given:

$ cat /tmp/so.csv
Light Green,"Matches type, instance, etc."
Red,Happens in BD10 but not BD20
Blue,"Instance and time matches, type doesn't match"
Yellow,Caught on replay

Try:

import csv
with open('/tmp/so.csv') as f:
    for line in csv.reader(f):
        print line

Prints:

['Light Green', 'Matches type, instance, etc.']
['Red', 'Happens in BD10 but not BD20']
['Blue', "Instance and time matches, type doesn't match"]
['Yellow', 'Caught on replay']

score 2 · Accepted Answer · answered Sep 09 '15 at 23:51

2

Stop the split after the first comma:

line = i.strip().split(",", 1)

answered Sep 09 '15 at 23:51

Brent Washburne

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@brent washburne, this solution IS cool. Just to be comprehensive, what if the sentence is in col1 and color is in col2, how would I tell python to not break on commas inside the sentence since your trick wouldn't work due to the breaking comma not being in the first occurrence? – Classified Sep 10 '15 at 00:11

How to create a list in python when the elements contain commas

3 Answers3