Track 8 · Lesson 4 of 11

Processing files line by line

Stream through large files one line at a time to count, filter, transform and write results without loading the whole file.

You will be able to

• Explain why looping over a file uses little memory however large the file is
• Split each line into fields and count or total values while streaming
• Filter matching lines into a new file, reading and writing at the same time
• Use enumerate() for line numbers and skip blank, comment and malformed lines