Combining string from csv into one line

Question

I am trying to read from csv file that only has one column. I need to combine all of the string into one for instance Row[1]=="Hallo." and Row[2]=="Goodbye." into string=="Hallo. Goodbye.".

import csv

data=None
with open('reviews.csv',encoding='utf-8') as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    line_count = 0
    for row in csv_reader:
        data2=(row[0])
        print(f'\n{data}.')
        line_count += 1
        data+=data2
    print(f'Processed {line_count} lines.')

Current error I'm getting is:

TypeError: unsupported operand type(s) for +=: 'NoneType' and 'str'

I have searched and read few posts but cannot seem to understand it.

Answer 1

Because you are joining a bunch of strings, try using the join method of a string with a simple generator comprehension:

import csv

with open('reviews.csv',encoding='utf-8') as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    data = "".join(row[0] for row in csv_reader if isinstance(row[0], str))

print(data)
print(f'Processed {csv_reader.line_num} lines')

Note that csv_reader internally keeps track of how many lines it has reviewed.

Answer 2

Make a test file to work with.

with open("/tmp/junk.txt", 'w') as f: 
    for i in range(10): 
        f.write("Hello {}\n".format(i)) 

Now open your file.

with open("/tmp/junk.txt", 'r') as f: 
    data = f.readlines()

Clean up the whitespace (trailing new lines).

data = [i.strip() for i in data] 

And finally join it back together, space delimited.

print(" ".join(data))                                                                                                                                                          
Hello 0 Hello 1 Hello 2 Hello 3 Hello 4 Hello 5 Hello 6 Hello 7 Hello 8 Hello 9

Answer 3

A file with one column isn't a CSV. It is just a file with lines. To join up all the lines:

with open('reviews.csv') as f:
    print(' '.join(f.read().splitlines()))