Converting Tuple inside of an array into a dictionary in Python

Question

I have been trying to solve this problem but I cannot get it right :( I am querying mySQL database in Django, and my results comes back as a tuple inside of an array. Please see dummy data below;

query_results = [
    (500, datetime.date(2017, 1, 1)),
    (302, datetime.date(2017, 1, 2)),
    (550, datetime.date(2017, 1, 3)),
    (180, datetime.date(2017, 1, 4)),
    (645, datetime.date(2017, 1, 5)),
    (465, datetime.date(2017, 1,6))
]

500, 302, 550 etc... are my records. The next element are the date of those records. I would like to append them into a dictionary using a loop, but I always get an error of:

TypeError: list indices must be integers, not tuple.

Can anyone please give me some advise on how to append these into something like this:

myDict = {
    "record": "",
    "date": ""
}

All help is greatly appreciated!

Answer 1

You could unpack the list of tuples and zip them into a dict with the keys you want,

dict(zip(['record', 'date'], zip(*query_results)))

which outputs

{'date': (datetime.date(2017, 1, 1),
          datetime.date(2017, 1, 2),
          datetime.date(2017, 1, 3),
          datetime.date(2017, 1, 4),
          datetime.date(2017, 1, 5),
          datetime.date(2017, 1, 6)),
 'record': (500, 302, 550, 180, 645, 465)}

Update

If you're hoping for a list of dicts, you could use a list comprehension directly.

[dict(record=record, date=date) for record, date in query_results]

which outputs

[{'date': datetime.date(2017, 1, 1), 'record': 500},
 {'date': datetime.date(2017, 1, 2), 'record': 302},
 {'date': datetime.date(2017, 1, 3), 'record': 550},
 {'date': datetime.date(2017, 1, 4), 'record': 180},
 {'date': datetime.date(2017, 1, 5), 'record': 645},
 {'date': datetime.date(2017, 1, 6), 'record': 465}]

Answer 2

Alternative format to Mitch's answer, as the post was a bit ambiguous on wanted result:

>list_of_dicts = [ {'result': tup[0], 'date': tup[1]} for tup in query_results]

>list_of_dicts[0]    
{'result':500, 'date':datetime.date(2017, 1, 1) }

Building on other disucssion if you would rather have each record key to a date time you can instead build a dictionary of each record as an entry. This assumes that the records will never be duplicates. In which case the comprehension would look like this:

my_dict = {str(record) : date for record, date in query_results}

where the dict looks like:

{"500": date1, "501", date2} #but not necessarily in order

Answer 3

This loop should do:

    my_dict = {}
    for item in query_results:
        my_dict[item[0]] = item[1]

This will stick your records (500, 550, etc.) as dictionary keys (item[0] part) so that you can easily call them out. And the value associated with those keys will be the datetime object (item[1] part).

If you want a more complicated solution please let us know.

Tom

Answer 4

If you want them as a tuple inside the dictionary, Mitch's answer would work.

If you want a separate dictionary in each loop, you can do:

for result in query_results:
    myDict = {}
    myDict["record"] = result[0]
    myDict["date"] = result[1]
    your_operation()

Or if you want the record as the key, and the date as the value (unless you have repeating records, this could be very useful) you can do:

myDict = {}
for result in query_results:
    myDict[result[0]] = result[1]

Then you would have:

myDict = {"500": datetime.date(2017, 1, 1), 
          "302": datetime.date(2017, 1, 2), 
          etc..}