Lambda function it's a non-bureaucratic way to create a function.
That's it. For example, let's supose you have your main function and need to square values. Let's see the traditional way and the lambda way to do this:
Traditional way:
def main():
...
...
y = square(some_number)
...
return something
def square(x):
return x**2
The lambda way:
def main():
...
square = lambda x: x**2
y = square(some_number)
return something
See the difference?
Lambda functions go very well with lists, like lists comprehensions or map. In fact, list comprehension it's a "pythonic" way to express yourself using lambda. Ex:
>>>a = [1,2,3,4]
>>>[x**2 for x in a]
[1,4,9,16]
Let's see what each elements of the syntax means:
[] : "Give me a list"
x**2 : "using this new-born function"
for x in a: "into each element in a"
That's convenient uh? Creating functions like this. Let's rewrite it using lambda:
>>> square = lambda x: x**2
>>> [square(s) for x in a]
[1,4,9,16]
Now let's use map, which is the same thing, but more language-neutral. Maps takes 2 arguments:
(i) one function
(ii) an iterable
And gives you a list where each element it's the function applied to each element of the iterable.
So, using map we would have:
>>> a = [1,2,3,4]
>>> squared_list = map(lambda x: x**2, a)
If you master lambdas and mapping, you will have a great power to manipulate data and in a concise way. Lambda functions are neither obscure nor take away code clarity. Don't confuse something hard with something new. Once you start using them, you will find it very clear.
