Python 2D数组-通过键获取值

Question

Suppose it is the following structure given:

from django.utils.translation import ugettext_lazy as _

# Constants for all available difficulty types.
SIMPLE = 1
MEDIUM = 2
DIFFICULT = 3

# Names for all available difficulty types.
DIFFICULTIES = (
    (SIMPLE, _("simple")),
    (MEDIUM, _("medium")),
    (DIFFICULT, _("difficult")),
)

How do you get the string value, if a constant is given?

A loop is easy to program, but is there a shorter python-like way with a single expression?

The expression

DIFFICULTIES[SIMPLE][1]

returns the string "medium". What is obviously wrong.

Answer 1

Of course you can use a dict, but the array is given.

So exchange it. (I'm assuming you kept the receipt..)

>>> dict(DIFFICULTIES)
{1: 'simple', 2: 'medium', 3: 'difficult'}
>>> d = dict(DIFFICULTIES)
>>> d[MEDIUM]
'medium'

Searching through an unsorted tuple for something simply isn't the right way to go about things. I suppose you could do

>>> next(v for k,v in DIFFICULTIES if k == MEDIUM)
'medium'

if you wanted to avoid a for loop with a colon, but that's a little silly.

Answer 2

it just because you specified a tuple, an indexing starting from 0, you either need to switch to dictionary or modify your constants with correct values:

DIFFICULTIES = {SIMPLE: "simple", MEDIUM: "medium", DIFFICULT: "difficult"}

OR:

SIMPLE, MEDIUM, DIFFICULT = range(3)

Answer 3

Use a dictionary:

SIMPLE, MEDIUM, DIFFICULT = range(3)
DIFFICULTIES = {
    SIMPLE: _("simple"),
    MEDIUM: _("medium"),
    DIFFICULT: _("difficult")
}
DIFFICULTIES[SIMPLE] # will return "simple"