What is not a row in a csv file?

Question

I came upon this code in a tutorial:

 for row in csv_reader:
        if not row:
            continue
        dataset.append(row)

Which I take to mean that if the code encounters something other than a row, just skip and continue. Is that correct?

What defines 'not row'?

Answer 1

This allows you to skip over empty lines in a CSV file.

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not row just means "row is falsey".

In Python, the following things are falsey:

• False
• None
• Numeric zeroes
• Empty containers

(Of course you can write your own class with a __bool__ method that does anything you want—but by convention, it should follow the same rule.)

This is all explained in Boolean operations in the docs.

--

The rows iterated by a csv.reader are lists. (And lists are containers, so they're falsey iff they're empty.)

An empty line produces an empty list; a line with text but no delimiters produces a list of one string; a line with delimiters produces a list of two or more strings.

This is covered in the csv module docs… but not really all in one place.