I have a function:
def csvToList( filename ):
with open(filename, 'r') as fp:
reader = csv.reader(fp)
myList = list(reader)
return myList
and call it with:
fruitList = csvToList('fruit.csv')
The contents of fruit.csv is:
apple,orange,kiwi,tomato
The value of fruitList is a list of lists:
[['apple', 'orange', 'kiwi', 'tomato']]
Why does this code produce a list of lists and not just a simple "flat" list, like this:
['apple', 'orange', 'kiwi', 'tomato']
The reader produces rows from a CSV file. See the documentation :
Each row read from the csv file is returned as a list of strings.
It doesn't matter here that your file only consists of 1 row; list(reader)
produces a list of all the rows, be that 0, 1 or 20 million. So a file with just 1 row gives you a list containing that single row as a list.
If you only ever expect one row, iterate one step with the next()
function :
def csvToList( filename ):
with open(filename, 'r') as fp:
reader = csv.reader(fp)
return next(reader, [])
next(reader, [])
tells the function to return an empty list if reader
doesn't produce anything at all.
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