TypeError: 'dict_values' and dict_key object is not subscriptable

Question

I met a problem with a old python 2x code syntax which produced the error:

print (name, tree.keys()[0])
TypeError: 'dict_keys' object is not subscriptable

and the old python 2x code is:

def printTree(self,tree,name):
        if type(tree) == dict:
            print name, tree.keys()[0]
            for item in tree.values()[0].keys():
                print name, item
                self.printTree(tree.values()[0][item], name + "\t")
        else:
            print name, "\t->\t", tree

How can I change these syntax in using python 3x? I have tried list() how ever the self.printTree(tree.values()[0][item], name + "\\t") still has the dict_value error.

The full code: https://homepages.ecs.vuw.ac.nz/~marslast/Code/Ch12/dtree.py

Thank you for your help.

Answer 1

There are many options to do it. Here are the shortest I know:

d = {1:2, 3:4}
list(d.keys())[0]  # option 1
next(iter(d.keys()))  # option 2
next(iter(d))  # option 3 - works only on keys (iteration over a dictionary is an iteration over its keys)

Answer 2

I hope it will be useful:

def printTree(products):
        if type(products) == dict:
            print(list(products.keys())[0])
            for item in products.values():
                print(item)
                self.printTree(products.values()[0][item], name + "\t")
        else:
            print("\t->\t", products)