Python csv text manipulation

Question

I want to combine combine fields from an input .csv file for output to a .csv file, and some contain commas. Here is my code, simplified

outfile = open('output.csv', 'w')

#these values are made up for this example; normally they would be read from
#a csv and passed to the following 'combine()' function

a = "John"  
b = ",Jr."  

def combine(a, b):  
    if a == "":  
        pass  #don't write anything if the field is empty
    else:  
        outfile.write(a)  
    if b =="":  
        pass  
    else:  
        outfile.write(b)

If b starts with a comma, how do I make the output "John, Jr." ? I have tried using the csv.writer writerow() but it puts a comma delimiter between each character. I have tried defining an escapechar but it just outputs "John \" , "Jr." Suggestions?

Community · Accepted Answer · 2021-10-07 05:57:16Z

4

If you would like to know details about CSV, there is a spec: https://www.rfc-editor.org/rfc/rfc4180

In general it states the following "Fields containing line breaks (CRLF), double quotes, and commas should be enclosed in double-quotes."

"If double-quotes are used to enclose fields, then a double-quote appearing inside a field must be escaped by preceding it with another double quote."

Implementations like Excel always put all field values into double quotes.

If you open a file for read or write you can specify the type of quoting directly

mcvs = csv.writer(open('file.csv', 'wb'), quoting=csv.QUOTE_ALL)

will always add quotes to the around the field value.

For all possible values look at the python documentation

http://docs.python.org/library/csv.html#module-csv

edited Oct 7, 2021 at 5:57

CommunityBot

11 silver badge

answered Feb 22, 2012 at 5:49

sebs

4,7963 gold badges21 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Brandon Dorris Over a year ago

I had solved it by manually double quoting around the entire "name" output field. I like this better because it makes my code more readable. Thank you!

Tim McNamara · Accepted Answer · 2012-02-22 05:51:56Z

1

csv.writer allows you to add a quoting keyword which can be used to control how things are quoted.

You probably want something like csv.QUOTE_MINIMAL.

>>> import csv
>>> with open('eggs.csv', 'wb') as outfile:
...     writer = csv.writer(outfile, quoting=csv.QUOTE_MINIMAL)
...     writer.writerow(['Spam'] * 5 + ['Baked Beans'])
...     writer.writerow(['Spam', 'Lovely Spam', 'Wonderful Spam'])

answered Feb 22, 2012 at 5:51

Tim McNamara

18.5k5 gold badges54 silver badges84 bronze badges

Comments

Blender · Accepted Answer · 2012-02-22 05:38:37Z

0

csv.writer writerow() expects a list of values:

foo.writerow(['John', ',Jr.'])

answered Feb 22, 2012 at 5:38

Blender

300k55 gold badges462 silver badges511 bronze badges

Comments

Guy Adini · Accepted Answer · 2012-02-22 05:42:25Z

0

And if you want to stick with pure Python:

resultStr = a+b
if ',' in resultStr: resultStr= '"' + resultStr + '"'

answered Feb 22, 2012 at 5:42

Guy Adini

5,5245 gold badges35 silver badges35 bronze badges

1 Comment

Brandon Dorris Over a year ago

This is very similar to the solution I used. I will be rewriting the script to specify quoting everything as mentioned it sebs post above.

Collectives™ on Stack Overflow

Python csv text manipulation

4 Answers 4

1 Comment

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related