Python elegant assignment based on True/False values

Question

I have a variable I want to set depending on the values in three booleans. The most straight-forward way is an if statement followed by a series of elifs:

if a a         


        

Answer 1

How about using a dict?

name = {(True, True, True): "first", (True, True, False): "second",
        (True, False, True): "third", (True, False, False): "fourth",
        (False, True, True): "fifth", (False, True, False): "sixth",
        (False, False, True): "seventh", (False, False, False): "eighth"}

print name[a,b,c] # prints "fifth" if a==False, b==True, c==True etc.

Answer 2

Maybe not much better, but how about

results = ['first', 'second', 'third', 'fourth', 
           'fifth', 'sixth', 'seventh', 'eighth']
name = results[((not a) << 2) + ((not b) << 1) + (not c)]

Answer 3

I'd go for the list/bits solution of @OscarRyz, @Clint and @Sven, but here's another one:

S1 = frozenset(['first', 'second', 'third', 'fourth'])
S2 = frozenset(['first', 'second', 'fifth', 'sixth'])
S3 = frozenset(['first', 'third', 'fifth', 'seventh'])
last = 'eighth'
empty = frozenset([])


def value(a, b, c):
    for r in (a and S1 or empty) & (b and S2 or empty) & (c and S3 or empty):
        return r
    return last

Answer 4

What about nested ifs - it means you don't have to check everything several times and reads clearer to me (although maybe not quite as clever as some of the other answers):

if a:
    if b:
        if c:
            name="first"
        else:
            name="second"
    else:
        if c:
            name="third"
        else:
            name="fourth"
else:
    if b:
        if c:
            name="fifth"
        else:
            name="sixth"
    else:
        if c:
            name="seventh"
        else:
            name="eighth"

Answer 5

if a,b,c are really booleans:

li = ['eighth', 'seventh', 'sixth', 'fifth', 'fourth', 'third', 'second', 'first']
name = li[a*4 + b*2 + c]

if they are not booleans:

li = ['eighth', 'seventh', 'sixth', 'fifth', 'fourth', 'third', 'second', 'first']
a,b,c = map(bool,(a,b,c))
name = li[a*4 + b*2 + c]

idea from Clint Miller