Python:使用带有变量的namedtuple._replace作为fieldname

Question

我可以使用变量引用namedtuple fieldame吗？

from collections import namedtuple
import random 

Prize = namedtuple("Prize", ["left", "right"]) 

this_prize = Prize("FirstPrize", "SecondPrize")

if random.random() > .5:
    choice = "left"
else:
    choice = "right"

#retrieve the value of "left" or "right" depending on the choice

print "You won", getattr(this_prize,choice)

#replace the value of "left" or "right" depending on the choice

this_prize._replace(choice  = "Yay") #this doesn't work

print this_prize

Answer 1

元组是不可变的,NamedTuples也是如此.它们不应该被改变!

this_prize._replace(choice = "Yay")调用_replace与关键字参数"choice".它不用choice作变量并尝试用名称替换字段choice.

this_prize._replace(**{choice : "Yay"} )将使用任何choice作为字段名称

_replace返回一个新的NamedTuple.你需要重新签名:this_prize = this_prize._replace(**{choice : "Yay"} )

只需使用字典或写一个普通的课程!