Question

In python,

how can i do something like that

a = ["pera", "uva", "maca", "saladamista"]
b = a.reverse()

but without assign the reverse list to a?

Answer 1

First copy the list, then reverse the copy:

a = ["pera", "uva", "maca", "saladamista"]
b = a[:]
b.reverse()

or use the “Martian smiley”:

b = a[::-1]

Edit: In case someone is interested in timings, here they are:

In [1]: a = range(100000)

In [2]: %timeit b = a[:]; b.reverse()
1000 loops, best of 3: 436 us per loop

In [3]: %timeit b = a[::-1]          
1000 loops, best of 3: 414 us per loop

In [4]: %timeit b = list(reversed(a))
1000 loops, best of 3: 823 us per loop