file.readlines leaving blank lines

file.readlines()

(and also file.readline()) includes the newlines.

Do

print i.replace('\n', '')

if you don't want them.

It may seem weird to include the newline at the end of the line, but this allows, for example, you to tell whether the last line has a newline character or not. That case in tricky in many languages' I/O.

file.readlines() return list of strings. Each string contain trailing newlines. print statement prints the passed parameter with newlnie.; That's why you got extra lines.

To remove extra newline, use str.rstrip:

print i.rstrip('\n')

or use sys.stdout.write

sys.stdout.write(i)

BTW, don't use file.readlines unless you need all lines at once. Just iterate the file.

with open("test.txt") as f:
    for i in f:
        print i.rstrip('\n')
        ...

UPDATE

In Python 3, to prevent print prints trailing newline, you can use print(i, end='').

In Python 2, you can use same feature if you do : from __future__ import print_function

Answer to UPDATE

Tabs, Newlines are also considers as whitespaces.

>> ' \r\n\t\v'.isspace()
True