NameError: name 'reduce' is not defined in Python
Question:
I’m using Python 3.2. Tried this:
xor = lambda x,y: (x+y)%2
l = reduce(xor, [1,2,3,4])
And got the following error:
l = reduce(xor, [1,2,3,4])
NameError: name 'reduce' is not defined
Tried printing reduce
into interactive console – got this error:
NameError: name 'reduce' is not defined
Is reduce
really removed in Python 3.2? If that’s the case, what’s the alternative?
Answers:
It was moved to functools
.
In this case I believe that the following is equivalent:
l = sum([1,2,3,4]) % 2
The only problem with this is that it creates big numbers, but maybe that is better than repeated modulo operations?
You can add
from functools import reduce
before you use the reduce.
Or if you use the six library
from six.moves import reduce
you need to install and import reduce from functools
python package
Reduce function is not defined in the Python built-in function.
So first, you should import the reduce function
from functools import reduce
Use it like this.
# Use reduce function
from functools import reduce
def reduce_func(n1, n2):
return n1 + n2
data_list = [2, 7, 9, 21, 33]
x = reduce(reduce_func, data_list)
print(x)
I’m using Python 3.2. Tried this:
xor = lambda x,y: (x+y)%2
l = reduce(xor, [1,2,3,4])
And got the following error:
l = reduce(xor, [1,2,3,4])
NameError: name 'reduce' is not defined
Tried printing reduce
into interactive console – got this error:
NameError: name 'reduce' is not defined
Is reduce
really removed in Python 3.2? If that’s the case, what’s the alternative?
It was moved to functools
.
In this case I believe that the following is equivalent:
l = sum([1,2,3,4]) % 2
The only problem with this is that it creates big numbers, but maybe that is better than repeated modulo operations?
You can add
from functools import reduce
before you use the reduce.
Or if you use the six library
from six.moves import reduce
you need to install and import reduce from functools
python package
Reduce function is not defined in the Python built-in function.
So first, you should import the reduce function
from functools import reduce
Use it like this.
# Use reduce function
from functools import reduce
def reduce_func(n1, n2):
return n1 + n2
data_list = [2, 7, 9, 21, 33]
x = reduce(reduce_func, data_list)
print(x)