>>> help(numpy.random.randint)
Help on built-in function randint:

randint(...) method of mtrand.RandomState instance
    # <snip>

    Parameters
    ----------
    low : int
        Lowest (signed) integer to be drawn from the distribution (unless
        ``high=None``, in which case this parameter is the *highest* such
        integer).

$ time python -c 'x = range(10); del x[-3:]'

real	0m0.066s
user	0m0.020s
sys	0m0.022s
$ time python -c 'x = range(10); x[-3:] = []'

real	0m0.066s
user	0m0.023s
sys	0m0.023s

import time
n=100000000
x = list(range(n))
t = time.time()
del x[-1000:]
s = time.time()
print(s-t)

x = list(range(n))
t = time.time()
x[-1000:]=[]
s = time.time()
print(s-t)

>>> range(100)[20:50]
range(20, 50)

>>> map(lambda x:x**2, range(100))[20:50]
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    map(lambda x:x**2, range(100))[20:50]
TypeError: 'map' object is not subscriptable