Why does converting a csv_reader object to a list ouput an empty list?

Question

I am trying to choose a random element from a csv file so I converted a csv_reader object to a list using the list() function but when I print it out, the list is empty. Why does this happen?

Code to replicate:

    with open('data.csv','r') as file:
        csvFile = csv.reader(file)
        row_count = sum(1 for row in csvFile)
        textToSend = list(csvFile)
        print(textToSend)
        #Outputs an empty list '[]'

Barmar · Accepted Answer · 2020-07-21 08:07:41Z

1

You already read the entire file in sum(1 for row in csvFile). There's nothng left to read when you do list(csvfile).

You can rewind the file back to the beginning to read it again.

with open('data.csv','r') as file:
    csvFile = csv.reader(file)
    row_count = sum(1 for row in csvFile)
    file.seek(0)
    textToSend = list(csvFile)
    print(textToSend)

Or you can read everything into a list first.

with open('data.csv','r') as file:
    csvFile = list(csv.reader(file))
    row_count = len(csvFile)
    textToSend = csvFile
    print(textToSend)

answered Jul 21, 2020 at 8:07

Barmar

789k57 gold badges554 silver badges669 bronze badges

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

Collectives™ on Stack Overflow

Why does converting a csv_reader object to a list ouput an empty list?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related