Print Dictionary Keys without Dictionary Name? How/why?

Question

So I created a dictionary for setting difficulty level on a little game.

diff_dict = {'easy':0.2, 'medium':0.1, 'hard':0.05} # difficulty level dict

Keys are going to be the difficulty names and the values some ratios that i would use to compute the difficulty.

So I was trying to figure out how to print only the keys to the user:

print('\nHere are the 3 possible choices: ',diff_dict.keys())

this would print as:

Here are the 3 possible choices:  dict_keys(['hard', 'easy', 'medium'])

Obviously I don't want to have the dictionary name displayed so I continued to search and I did find a solution which works:

diff_keys = diff_dict.keys()
print ('\nHere are the 3 possible choices: ',list(diff_keys))

But I still want to know if there are other methods to achieve this, then why and so on. So here I go with the Qs:

1. Can I achieve the same result without crating a new element, such as diff_keys?

2. Why does diff_dict.keys display the dict. name? Am I doing something wrong?

3. On a side note, how can I print keys or other elements like lists, tuples, etc without the string quotes (')?

4. same as #3 above but the brackets ([ ])

thanks and cheerio :-)

Answer 1

The thing is, in Python 3 dict's method keys() does not return a list, but rather a special view object. That object has a magic __str__ method that is called on an object under the hood every time you print that object; so for view objects created by calling keys() __str__ is defined so that the resulting string includes "dict_keys".

Look for yourself:

In [1]: diff_dict = {'easy': 0.2, 'medium': 0.1, 'hard': 0.05}

In [2]: print('Here are the 3 possible choices:', diff_dict.keys())
Here are the 3 possible choices: dict_keys(['medium', 'hard', 'easy'])

In [3]: diff_dict.keys().__str__()
Out[3]: "dict_keys(['medium', 'hard', 'easy'])"

Note that 99.9% of the time you don't need to call this method directly, I'm only doing it to illustrate how things work.

Generally, when you want to print some data, you almost always want to do some string formatting. In this case, though, a simple str.join will suffice:

In [4]: print('Here are the 3 possible choices:', ', '.join(diff_dict))
Here are the 3 possible choices: medium, hard, easy

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So, to answer you questions:

Can I achieve the same result without crating a new element, such as diff_keys?

An example is shown above.

Why does diff_dict.keys display the dict. name? Am I doing something wrong?

Because its __str__ method works that way. This is what you have to deal with when printing objects "directly".

how can I print keys or other elements like lists, tuples, etc without the string quotes (')?

same as #3 above but the brackets ([ ])

Print them so that their __str__ is not called. (Basically, don't print them.) Construct a string in any way you like, crafting your data into it, then print it. You can use string formatting, as well as lots of useful string methods.