如何向 python 中的空集添加项

我有以下程序:

def myProc(invIndex, keyWord):
D={}
for i in range(len(keyWord)):
if keyWord[i] in invIndex.keys():
D.update(invIndex[query[i]])
return D

但我得到了以下错误:

Traceback (most recent call last):
File "<stdin>", line 3, in <module>
TypeError: cannot convert dictionary update sequence element #0 to a sequence

如果 D 包含元素，我不会得到任何错误。但是我需要 D 在开始时是空的。

python
set

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小开

最佳答案

D = {} is a dictionary not set.

>>> d = {}
>>> type(d)
<type 'dict'>

Use D = set():

>>> d = set()
>>> type(d)
<type 'set'>
>>> d.update({1})
>>> d.add(2)
>>> d.update([3,3,3])
>>> d
set([1, 2, 3])

小开

>>> d = {}
>>> D = set()
>>> type(d)
<type 'dict'>
>>> type(D)
<type 'set'>

What you've made is a dictionary and not a Set.

The update method in dictionary is used to update the new dictionary from a previous one, like so,

>>> abc = {1: 2}
>>> d.update(abc)
>>> d
{1: 2}

Whereas in sets, it is used to add elements to the set.

>>> D.update([1, 2])
>>> D
set([1, 2])

小开

When you assign a variable to empty curly braces {} eg: new_set = {}, it becomes a dictionary. To create an empty set, assign the variable to a 'set()' ie: new_set = set()