CODEWITHSUNDEEP
pythoncsv
bigTree
bigTree

Reputation: 2183

Writing csv file in Python: unwanted commas appear

I'm trying to extract a list of dictionary values into a file with the following code:

import csv

def function(file, output, deli = ','):

    dictionary = dict()
    with open(file, 'r') as source, open(output, 'w') as outp:
        data = csv.reader(source)
        line0 = next(data)
        i = 0
        for element in line0:
            dictionary[i] = element
            i += 1
        my_writer = csv.writer(outp)
        for element in dictionary.values():
            print(element)
            my_writer.writerow(element)

if __name__ == '__main__':
    from sys import argv
    if len(argv) == 2:
        function(argv[1])
    elif len(argv) == 3:
        function(argv[1], argv[2])
    elif len(argv) == 4:
        function(argv[1], argv[2], argv[3])

    print("ok")

To run this code on the shell, I use the command: python function.py input output

However, trying on a csv file like: alpha, beta, gamma, delta

I get the following result:

a,l,p,h,a

 ,b,e,t,a

 ,g,a,m,m,a

 ,d,e,l,t,a

I tried to change the delimiter to ' ' and I got the same result with spaces instead of commas.

Am I missing something?

Upvotes: 1

Views: 2686

Answers (2)

RedBaron
RedBaron

Reputation: 4755

The problem is in the lines

for element in dictionary.values():
    print(element)
    my_writer.writerow(element)

From the docs argument to writerow should be a list of objects. In your case the argument is a string (which is iterable). So what you are actually doing is my_writer.writerow("alpha") which is written as a,l,p,h,a.

You should simply do

my_writer.writerow(element.values())

Also, you are getting leading commas beacuse your CSV string is alpha, beta, gamma. So when the split happens the elements are ['aplha',' beta',' gamma',]. You could use strip() to remove them

Upvotes: 2

John
John

Reputation: 13699

You are looping over the characters in the line instead of the actual elements

with open(file_, 'r') as source, open(output, 'w') as outp:
    data = csv.reader(source, delimiter=deli)
    #line0 = next(data)
    i = 0
    for element in data:
        dictionary[i] = element
        i += 1

also it's considered to be good practice to not override the built-ins in this case you are overriding file, instead PEP 008 recommends that you add an underscore to the end of you variable name.

Upvotes: 0

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