python: 'dict' object has no attribute 'has_key'

Question

I have this piece of code:

def separate_sets(self):
    self.groups = {}
    self.group_names = list(set(self.y))
    if len(self.group_names) > 2:
        print ('more than two classes provided...exiting')
        sys.exit()
    #putting all the samples in a regular order so that their
    #grouping can be easier.
    combined  = sorted(zip(self.x, self.y), key = lambda n: n[1])
    #--doing val,key here because (x,y) was zipped
    for val,key in combined:
        if self.groups.has_key(key):
            self.groups[key].append(val)
        else:
            self.groups[key] = []
            self.groups[key].append(val)
    #train on each group
    self.train()

And I received the following error message:

if self.groups.has_key(key):

AttributeError: 'dict' object has no attribute 'has_key'

What about the error is not clear? has_key was deprecated. Are you using Python 3 by any chance? — Felix Kling
– Felix Kling, Commented Oct 11, 2017 at 0:37

Óscar López · Accepted Answer · 2017-10-11 00:38:27Z

16

In Python 3.x, has_key() was removed, see the documentation. Hence, you have to use in, which is the pythonic way:

if key in self.groups:

answered Oct 11, 2017 at 0:38

Óscar López

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Comments

galaxyan · Accepted Answer · 2017-10-11 00:36:03Z

4

In python you could use "in" to check

 if key in self.groups:

answered Oct 11, 2017 at 0:36

galaxyan

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Comments

chepner · Accepted Answer · 2017-10-11 00:40:01Z

2

You can eliminate the whole if statement by using the setdefault method

    self.groups.setdefault(key, []).append(val)

answered Oct 11, 2017 at 0:40

chepner

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2 Comments

Sumin Jeong Over a year ago

oh, you mean the whole 'if' to 'else' ?

chepner Over a year ago

Yes. setdefault returns a reference to self.groups[key], or [] if key isn't in the dict. Either way, you can then add val to the resulting list.

Victor Castillo Torres · Accepted Answer · 2017-10-11 00:39:02Z

0

As of python 3.x has_key was removed, now you have to use the in operator

answered Oct 11, 2017 at 0:39

Victor Castillo Torres

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2 Comments

cs95 Over a year ago

Did you not see the other 2 answers with identical content?

Victor Castillo Torres Over a year ago

@cᴏʟᴅsᴘᴇᴇᴅ posted same time as the Óscar López answer ;)

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