How to can I write elements from several lists to csv in which each element belongs to each row?

Question

Please help me with this problem about csv files. I have 2 lists, and I want to write them to a csv file, like this:

X = [12,423,56]
Y = [35,78,321]

The csv file also contains one index column "No" which is auto-generated:

No,X,Y
1,12,35
2,423,78
3,56,321

Answer 1

You can do this with the csv module from the standard library, and the zip and enumerate builtin functions.

with open('myfile.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    # Write column headers
    writer.writerow(['No', 'X', 'Y'])
    for i, (a, b) in enumerate(zip(X,Y), start=1):
        writer.writerow([i, a, b])

Output:

No,X,Y
1,12,35
2,423,78
3,56,321

The csv module provides tools for reading and writing csv files.

enumerate outputs the index of each iteration of a loop; here we configure it to use 1 as it's starting value - by default it starts at zero.

zip accepts one or more iterables as input, loops over each iterable in-step and yields the elements from succeeding positions in the iterables each time:

• first iteration: yield item 0 from each iterable
• second iteration: yield item 1 from each iterable

etc.

If the iterables are not all of the same length. zip stops yielding once the shortest iterable has been consumed.