Question

I have the following code:

for node, value in sorted(d.iteritems()):
    outfile.write([node] + value)
    print(node, value)

I read a few different SO posts about this and am still somewhat confused. The print statement works perfectly, printing the key and value correctly in the interpreter. But I couldn’t figure out a way to get the outfile.write() statement to work here. Would greatly appreciate any clarification!

Answer 1

print automatically converts the given variable to a string (using the __repr__ method). file.write does not. You could still write to a file with something like:

outfile.write("%s %s\n" % (node, value))

(I also added a newline). However, you don’t make clear in the question what the types of node and value are. The expression [node] + value implies that value is a list. If you want the list to be comma separated (as implied by your question’s title) you can combine them and join them with commas like so:

outfile.write(",".join(map(str, [node] + value)))