>>> n = [1,2,3,4]
>>> filter(lambda x:x>3,n)
<filter object at 0x0000000002FDBBA8>
>>> len(filter(lambda x:x>3,n))
Traceback (most recent call last):
File "<pyshell#3>", line 1, in <module>
len(filter(lambda x:x>3,n))
TypeError: object of type 'filter' has no len()
I could not get the length of the list I got. So I tried saving it to a variable, like this...
>>> l = filter(lambda x:x>3,n)
>>> len(l)
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
len(l)
TypeError: object of type 'filter' has no len()
Instead of using a loop, is there any way to get the length of this?
You have to iterate through the filter object somehow. One way is to convert it to a list:
l = list(filter(lambda x: x > 3, n))
len(l) # <--
But that might defeat the point of using filter()
in the first place, since you could do this more easily with a list comprehension:
l = [x for x in n if x > 3]
Again, len(l)
will return the length.