Insert new line in CSV at second row via Python

Question

Is it possible to insert a new line in a CSV file at the 2nd row? For example, I have a CSV with column names and their values:

meter_id, sdp_id, lat, lon 813711, 1331, 34.298, -83.113

The application I'm attempting to read this file into requires a new line added indicating the column type. In the above example all would be string, so the CSV would need to be:

meter_id, sdp_id, lat, lon String, String, String, String 813711, 1331, 34.298, -83.113

I've read several posts how to add a new line at the end of the CSV, but couldn't find anything on how to do the above.

Possible duplicate of Insert line at middle of file with Python? — Mike Scotty
– Mike Scotty, Commented Jun 5, 2018 at 13:18

Rakesh · Accepted Answer · 2018-06-05 13:20:39Z

4

This is one approach using csv module.

Demo:

import csv toAdd = ["String", "String", "String", "String"] with open(filename, "r") as infile: reader = list(csv.reader(infile)) reader.insert(1, toAdd) with open(filename, "w") as outfile: writer = csv.writer(outfile) for line in reader: writer.writerow(line)

answered Jun 5, 2018 at 13:20

Rakesh

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4 Comments

J. Skinner Over a year ago

thank you for this answer. It's working, but it is entering an empty row between is row in the updated CSV.

Rakesh Over a year ago

Use with open(filename, "w", newline='') as outfile: if you are in python3

J. Skinner Over a year ago

I'm using Python 2.7.14.

Rakesh Over a year ago

Then use with open(filename, "wb") as outfile:

CLeo-Dev · Accepted Answer · 2018-06-05 13:22:19Z

A simple solution could be:

import csv row = ['String', ' String', ' String'] with open('file.csv', 'r') as readFile: reader = csv.reader(readFile) lines = list(reader) lines.insert(1, row) with open('file.csv', 'w') as writeFile: writer = csv.writer(writeFile) writer.writerows(lines) readFile.close() writeFile.close()

I could not try it. Please let me know if it works.

Thanks, one thing I'm noticing is that this is adding an extra row between each row in the updated CSV.

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