[Tutor] Getting first item in dictionary

[David L Neil]

On 28/01/20 7:16 AM, Alan Gauld via Tutor wrote:
> On 27/01/2020 11:51, S D wrote:
>> I have a dictionary which contains one item (“current_location”, which is a
>> nested dict) and I would like to access that nested dict. However, I cannot
>> use the key as the code will break if a different key is passed, e.g.
>> “different_location".
> 
> That doesn't make much sense. If you cannot use a key to
> access the data why did you put it in a dictionary which
> is a structure accessed by keys?

+1
(however, if we're going to abuse data structures, please see below)


> When you say the code will break if you use a wrong key
> surely all you should get is a Keyerror? And you can avoid
> that by using  dict.get(key) which returns None if the key
> is not found. (Although using try/except to catch the error
> would be better in this scenario because you should want
> to know why you have a wrong key and prevent it!
> 
>> How can I access the first item in a dictionary without using a key?
> 
> If that's what you really want you should be using a list
> instead of a dictionary.
> 
> But you can kind of get that by using dict.values() which
> gives you back a list of values (actually a fancy type
> of structure that acts like a list)

+1
see below...


>> dict looks like this:
>>
>> ```
>> {'current_location': {'date': '2020-01-27T10:28:24.148Z', 'type_icon':
>> 'partly-cloudy-day', 'description': 'Mostly Cloudy', 'temperature': 68.28,
>> 'wind': {'speed': 10.48, 'bearing': 178, 'gust': 12.47}, 'rain_prob': 0.02,
>> 'latitude': '-33.927407', 'longitude': '18.415747', 'request_id': 31364,
>> 'request_location': 'Current location'}}
>> ```
> 
> Have you considered creating a class?
> With that amount of nested dicts etc I'd have thought
> a class would be a better fit. Then maybe a list of instances.

+1

python3
Python 3.7.5 (default, Dec 15 2019, 17:54:26)
[GCC 9.2.1 20190827 (Red Hat 9.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
 >>> d = {'current_location': {'date': '2020-01-27T10:28:24.148Z', 
'type_icon':
... 'partly-cloudy-day', 'description': 'Mostly Cloudy', 'temperature': 
68.28,
... 'wind': {'speed': 10.48, 'bearing': 178, 'gust': 12.47}, 
'rain_prob': 0.02,
... 'latitude': '-33.927407', 'longitude': '18.415747', 'request_id': 31364,
... 'request_location': 'Current location'}}
 >>> list( d.values() )[ 0 ]
{'date': '2020-01-27T10:28:24.148Z', 'type_icon': 'partly-cloudy-day', 
'description': 'Mostly Cloudy', 'temperature': 68.28, 'wind': {'speed': 
10.48, 'bearing': 178, 'gust': 12.47}, 'rain_prob': 0.02, 'latitude': 
'-33.927407', 'longitude': '18.415747', 'request_id': 31364, 
'request_location': 'Current location'}
 >>> # alternately
 >>> d[ list( d.keys() )[ 0 ] ]
{'date': '2020-01-27T10:28:24.148Z', 'type_icon': 'partly-cloudy-day', 
'description': 'Mostly Cloudy', 'temperature': 68.28, 'wind': {'speed': 
10.48, 'bearing': 178, 'gust': 12.47}, 'rain_prob': 0.02, 'latitude': 
'-33.927407', 'longitude': '18.415747', 'request_id': 31364, 
'request_location': 'Current location'}


Why do you have a dict without knowing its key(s)?
If calling an API realises this data, surely the call includes 
sufficient data to be, or to assemble, the key?
-- 
Regards =dn