在 python 中打印不可转换为列表的 map object 的结果

Question

I was attempting to try out map function and end up with the following:

x=[1,2,-3,4]
result=(map(sum,x))
print(list(result))

Result:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-19-5270e85794e8> in <module>
      1 result=(map(sum,x))
----> 2 print(list(result))

TypeError: 'int' object is not iterable

I understand the reason for the error above but please help me with how to print the result.

Answer 1

map does a delayed execution, so when you cast the result to a list, the map is executed, which amounts in computing sum(1) , sum(2) , sum(-3) and sum(4)

Any of those will fail because sum takes something like a list (an iterable object) in input. You pass integers which are not iterable, hence the error message.

As suggested in the comments, you want to do a simple sum(x) .