Python LAMBDA expression

Anonymous Functions

• A lambda function is a minimal function that quickly defines a single line, and can be used wherever a function is needed
  As an example:

>>> def f(x,y):...     return x*y...>>> f(2,3)6>>> g = lambda x,y:x*y>>> g(2,3)6>>> g<function0x103e12c08>

1. When using Python to write some execution scripts, using lambda eliminates the process of defining a function, making the code more streamlined.
2. For some abstract functions that are not reused elsewhere, sometimes it is difficult to name a function, and using lambda does not have to consider naming problems.
3. Using lambda makes your code easier to understand at some point.
4. In a lambda statement, the colon is preceded by a parameter, which can have multiple, comma-separated. After the colon is the return value. A lambda statement is actually built as a function object.

Recursive

5*4*3*2*1120>>> def f(n):...     if0:...         return n*f(n-1)...     if0:...         return1...>>> f(5)120

• But recursion is not so well understood, so we're leading to reduce

Reduce

You need to define a function to help reduce

>>> l = range(1,6)>>> l[12345]>>> def f(x,y):...     return x*y...>>> reduce(f,l)120

Here we find that the function of defining f is not necessary and can be converted into lambda instead.

>>> reduce(lambda x,y:x*y, l)120

This avoids meaningless function definitions.

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Python Lambda expression