Python Conditional Variable Setting

Question

For some reason I can't remember how to do this - I believe there was a way to set a variable in Python, if a condition was true? What I mean is this:

 value = 'Test' if 1 == 1

Where it would hopefully set value to 'Test' if the condition (1 == 1) is true. And with that, I was going to test for multiple conditions to set different variables, like this:

 value = ('test' if 1 == 1, 'testtwo' if 2 == 2)

And so on for just a few conditions. Is this possible?

Solution 1

This is the closest thing to what you are looking for:

value = 'Test' if 1 == 1 else 'NoTest'

Otherwise, there isn't much else.

Solution 2

You can also do:

value = (1 == 1 and 'test') or (2 == 2 and 'testtwo') or 'nope!'

I prefer this way :D

Solution 3

Less obvious but nice looking term:

value = ('No Test', 'Test')[1 == 1]
print(value) # prints 'Test'

Comments

[oldboy]

it's called a Ternary Operator

[SolarLune]

Ah, I was missing the 'else', and it didn't tell me I needed one. I guess I should've known better, since if the condition doesn't equate, it wouldn't be set to anything. Thanks!

[James]

In case it isn't obvious, you can chain these (as in value = v1 if c1 else v2 if c2 else v3). An alternative is to use a dictionary.

[Chris]

Let's please have it obvious. We code for humans. Not for machines. The machines can read anything that's not an error, alright. But humans cannot. And it's us that make the mistakes so we have to make it easier for us. :)

[Ekrem Dinçel]

It looks good, but this will not work as we want: value = (1 == 1 and '') or (2 == 2 and 'testtwo') or 'nope!'

[rocksNwaves]

I actually like this a lot. It's quite understandable (and I happen to be a human). Thanks for sharing this extra tidbit. Cheers!

[Borjovsky]

Tip: The use of 'else' is mandatory here. But if the variable already exists, and you don't want it to change if the condition is not satisfied, just make it equal to itself: value = 'Test' if 1 == 1 else value