How can I add items to an empty set in python

Question

I have the following procedure:

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

But I am getting the following error:

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

I do not get any error if D contains elements. But I need D to be empty at the beginning.

Answer 1

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]) 

Answer 2

>>> 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])