Efficient string multiplication in Python

string_multiply.py

import timeit

test_str = "hello world|"
test_times = 1000

def test_str_add():
    result = ""
    for i in xrange(test_times-1):
        result += test_str
    return result

def test_str_join():
    return ''.join(test_str for i in xrange(test_times))

def test_str_nat():
    return test_str * test_times

def test_str_oth():
    return ''.join([test_str] * test_times)



print "   add: ", timeit.timeit(stmt=test_str_add, number=10000)
print "  join: ", timeit.timeit(stmt=test_str_join, number=10000)
print "native: ", timeit.timeit(stmt=test_str_nat, number=10000)
print " other: ", timeit.timeit(stmt=test_str_oth, number=10000)

# Moral of the story: Avoid for loops or repeatedly creating new strings (they're immutable)

cheers @peterldowns

Nice addition. Funnily,

''.join([test_str] * test_times)

is much faster than

''.join((test_str,) * test_times)