Mar 8, 2011 · assign_command = lambda dictionary, command: lambda command_function: dictionary.setdefault(command, command_function) This is a decorator. Put before a command we'd have from the LexYacc parser: @assign_command(_command_handlers, 'COMMAND') This essentially builds a python script from the LexYacc language defined. Or, a bit simpler:

@J.F. Sebastian, yes, "operator.itemgetter" ,and hundreds of other short functions one would have to know by heart, each to one specific use -- or use lambda, where one can create a generic expression in place, without having to recall exactly which short function does that one job.

@Javier I agree with you if you are talking about "lambda" the concept; however, if we're talking about "lambda" the python keyword then: 1) named functions are faster and can do more (statements+expressions) almost anywhere you would use lambdas (map+filter) you can just generator expressions or list comprehensions which are more performant ...

Because a lambda is (conceptually) the same as a function, just written inline. Your example is equivalent to . def f(x, y) : return x + y just without binding it to a name like f. Also how do you make it return multiple arguments? The same way like with a function. Preferably, you return a tuple: lambda x, y: (x+y, x-y)

May 31, 2013 · p = lambda x: (lambda x: x%2)(x)/2 Note in Python 2 this example will always return 0 since the remainder from dividing by 2 will be either 0 or 1 and integer-dividing that result by 2 will result in a truncated 0 .

Aug 22, 2023 · I have been going through a tutorial on lambda functions and came across this line of code to evaluate if a number is odd or even. And I do not understand how the tow logic operators work in this function. (lambda x: (x % 2 and 'odd' or 'even'))(5) 'odd' A more "usual/readable" way of doing it might be: (lambda x: 'even' if x % 2 == 0 else 'odd ...

Oct 12, 2015 · The code inside the lambda might iterate something, but only in the same ways as any other function might use (provided they are expressions, and so valid inside a lambda). In the example you mention using sorted , the key function is called on each element of the list being sorted - but it is sorted itself that does this, and which does the ...

Dec 11, 2008 · Since type is the default class of a python class object, and calling a class creates a new instance of that class, calling type with the correct arguments will result in a new class. my_class = type("my_class", (object,), {"an_attribute": 1})

Python has setattr function to set attribute of given object. You can use it in your lambda expression. setattr is useful when you want to programmatically-correctly (sorry) set some class or class' instance. It is not used frequently because it is easier to assign variables directly with = expression. But for lambdas... It is a salvation.

Jan 26, 2009 · We can now use new python syntax to make it way shorter and easier to read: Fibonacci: >>> (f:=lambda x: 1 if x <= 1 else f(x - 1) + f(x - 2))(5) 8 Factorial: >>> (f:=lambda x: 1 if x == 0 else x*f(x - 1))(5) 120 We use := to name the lambda: use the name directly in the lambda itself and call it right away as an anonymous function.