python list concatenation efficiency

Question

What is the most efficient way to concatenate two lists list_a and list_b when:

• list_b items have to be placed before

Answer 1

Why not just timeit?

import timeit

create_data = """\
list_a = range(10)
list_b = range(10)
"""

t1 = timeit.Timer(stmt=create_data + """\
list_a = list_b + list_a
""")

t2 = timeit.Timer(create_data + """\
for item in list_b:
    list_a.insert(0, item)
""")

t3 = timeit.Timer(create_data + """\
for item in list_a:
    list_b.append(item)
list_a = list_b
""")

t4 = timeit.Timer(create_data + """\
list_a[0:0] = list_b
""")

for i, t in enumerate([t1,t2,t3,t4]):
    print i, "%.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)

Result:

0 0.73 usec/pass
1 2.79 usec/pass
2 1.66 usec/pass
3 0.77 usec/pass