python - Add header to CSV without loading CSV

Question

Is there a way to add a header row to a CSV without loading the CSV into memory in python? I have an 18GB CSV I want to add a header to, and all the methods I've seen require loading the CSV into memory, which is obviously unfeasible.

Answer 1

You will need to rewrite the whole file. Simplest is not to use python

echo 'col1, col2, col2,... ' > out.csv
cat in.csv >> out.csv

Python based solutions will work at much higher levels and will be a lot slower. 18GB is a lot of data after all. Better to work with operating system functionality, which will be the fastest.