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I am trying to use 3 if statements within a python lambda function. Here is my code:

y=lambda symbol: 'X' if symbol==True 'O' if symbol==False else ' '

I Have been able to get two if statements to work just fine e.g.

x=lambda cake: "Yum" if cake=="chocolate" else "Yuck"

Essentially, I want a lambda function to use if statements to return 'X' if the symbol is True, 'O' if it is false, and ' ' otherwise. I'm not even sure if this is even possible, but I haven't been able to find any information on the internet, so I would really appreciate any help :)

Rational Function
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  • If symbol is a boolean, it can only have two values. What could ever trip the last `else`? – ddsnowboard Oct 30 '15 at 15:26
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    @ddsnowboard almost anything which is not a boolean. – bereal Oct 30 '15 at 15:31
  • @bereal So the idea is that `symbol` could be of any type? – ddsnowboard Oct 30 '15 at 15:35
  • @bereal is right, I have a list which contains True, False, or None. I want my code to convert None to ' ', so None would trip this else statement. I can understand why you might have found this confusing though, because it does seem like symbol is a Boolean without any context from the rest of my code. – Rational Function Oct 30 '15 at 15:36

3 Answers3

28

You are missing an else before 'O'. This works:

y = lambda symbol: 'X' if symbol==True else 'O' if symbol==False else ' '

However, I think you should stick to Adam Smith's approach. I find that easier to read.

Community
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Cristian Lupascu
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You can use an anonymous dict inside your anonymous function to test for this, using the default value of dict.get to symbolize your final "else"

y = lambda sym: {False: 'X', True: 'Y'}.get(sym, ' ')
Adam Smith
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  • Thank you, this is very helpful. I ticked w0lf's answer, because it exactly answered my question, but your approach is definitely more pythonic and logical. – Rational Function Oct 30 '15 at 15:40
  • @PM2Ring Whoops, right, because you're testing for equivalence to the value `True` and the value `False`, rather than testing for Truthyness or Falsyness. I'll edit – Adam Smith Oct 30 '15 at 16:01
1

This is one way where you can try multiple if else in lambda function

Example,

largest_num = lambda a,b,c : a if a>b and a>c else b if b>a and b>c else c if c>a and c>b else a

largest_num(3,8,14) will return 14

Nikolas Charalambidis
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DB_Arch
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