如何在函数和Lambda中使用.count（）

Question

I am a beginner of python, thank you so much!

function:

def count(c):
    return c.count(1)

count(1,1,1,11,1,12,1)

This function doesn't work, I want to create a function count how many 1 's?

lambda:

counts = lambda m:count('m') 
counts('what is you name, my name is mammy!')

This lambda doesn't work, too. I want to create a lambda count how many 'm' 's?

Answer 1

Just add a * in front of c to make it take all the leftover arguments and sets it to a list

def count(*c):
    return c.count(1)

count(1,1,1,11,1,12,1)

and the lambda function can be:

counts = lambda m: m.count('m') 
counts('what is you name, my name is mammy!')

Answer 2

Your first example fails because you're passing multiple arguments, and it only accepts one (presumably a list ). One way to fix it would be to pass a list :

def count(c):
    return c.count(1)

print(count([1,1,1,11,1,12,1]))  # 5

Another way to fix it is to allow multiple parameters but treat them as a list . Here's how you can do that:

def count(*c):
    return c.count(1)

print(count(1,1,1,11,1,12,1))  # 5

Your second example is missing a thing to call count on. Again, one possible fix:

counts = lambda x: x.count('m')
print(counts('what is you name, my name is mammy!'))  # 6