Printing without newline (print 'a',) prints a space, how to remove?

You can suppress the space by printing an empty string to stdout between the print statements.

>>> import sys
>>> for i in range(20):
...   print 'a',
...   sys.stdout.write('')
... 
aaaaaaaaaaaaaaaaaaaa

However, a cleaner solution is to first build the entire string you'd like to print and then output it with a single print statement.

There are a number of ways of achieving your result. If you're just wanting a solution for your case, use string multiplication as @Ant mentions. This is only going to work if each of your print statements prints the same string. Note that it works for multiplication of any length string (e.g. 'foo' * 20 works).

>>> print 'a' * 20
aaaaaaaaaaaaaaaaaaaa

If you want to do this in general, build up a string and then print it once. This will consume a bit of memory for the string, but only make a single call to print. Note that string concatenation using += is now linear in the size of the string you're concatenating so this will be fast.

>>> for i in xrange(20):
...     s += 'a'
... 
>>> print s
aaaaaaaaaaaaaaaaaaaa

Or you can do it more directly using sys.stdout.write(), which print is a wrapper around. This will write only the raw string you give it, without any formatting. Note that no newline is printed even at the end of the 20 as.

>>> import sys
>>> for i in xrange(20):
...     sys.stdout.write('a')
... 
aaaaaaaaaaaaaaaaaaaa>>> 

Python 3 changes the print statement into a print() function, which allows you to set an end parameter. You can use it in >=2.6 by importing from __future__. I'd avoid this in any serious 2.x code though, as it will be a little confusing for those who have never used 3.x. However, it should give you a taste of some of the goodness 3.x brings.

>>> from __future__ import print_function
>>> for i in xrange(20):
...     print('a', end='')
... 
aaaaaaaaaaaaaaaaaaaa>>> 

From PEP 3105: print As a Function in the What’s New in Python 2.6 document:

>>> from __future__ import print_function
>>> print('a', end='')

Obviously that only works with python 3.0 or higher (or 2.6+ with a from __future__ import print_function at the beginning). The print statement was removed and became the print() function by default in Python 3.0.