Append a Header for CSV file?

Question

I am trying to add a header to my CSV file.

I am importing data from a .csv file which has two columns of data, each containing float numbers. Example:

Answer 1

In this case, You don't need the CSV module. You need the fileinput module as it allows in-place editing:

import fileinput

for line in fileinput.input(files=['mycsvfile.csv'], inplace=True):
    if fileinput.isfirstline():
        print 'ColA,ColB'
    print line,

In the above code, the print statement will print to the file because of the inplace=True parameter.