Python csv没有写入文件

Question

I am trying to write to a .tsv file using python's CSV module, this is my code so far

file_name = "test.tsv"
TEMPLATE = "template.tsv"
fil = open(file_name, "w")
# Added suggested change 
template = csv.DictReader(open(TEMPLATE, 'r'), delimiter='\t')
new_file = csv.DictWriter(fil, fieldnames=template.fieldnames, delimiter='\t')
new_file.writeheader()

basically TEMPLATE is a file that will contain the headers for the file, so i read the headers using DictReader and pass the fieldnames to DictWriter , as far as i know the code is fine, the file test.tsv is being created but for some reason the headers are not being written.

Any help as to why this is happening is appreciated, thanks.

Answer 1

DictReader's first argument should be a file object (create with open() ), cf. http://docs.python.org/py3k/library/csv.html#csv.DictReader

You forgot open() for the TEMPLATE file.

import csv

file_name = "test.tsv"
TEMPLATE = "template.tsv"
fil = open(file_name, "w")

# you forgot this line, which will open the file
template_file = open(TEMPLATE, 'r')

template = csv.DictReader(template_file, delimiter='\t')
new_file = csv.DictWriter(fil, fieldnames=template.fieldnames, delimiter='\t')
new_file.writeheader()

Answer 2

Try to give DictReader opened file instead of file name:

csv.DictReader(open(TEMPLATE, 'r'), delimiter='\t')

Same for the writer, but opened for writing.