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Python dictionary sort list with null values ​​at the end

I have a homogeneous list of null-valued dictionaries, but it can contain any value types. Example:

values=[{'buy_qty': 15, 'product_id': 30}, {'buy_qty': 0,'product_id': 33},{'buy_qty': 25, 'product_id': 50}, {'buy_qty': 7, 'product_id': 22}]

Is there a way, without reinventing the wheel, to get the list sorted by the "minimum" buy_qty "usually for the python path, but the" null "values ​​at the end of the list, for example:

values=[{'buy_qty': 7, 'product_id': 22}, {'buy_qty': 15, 'product_id': 30}, {'buy_qty': 25, 'product_id': 50}, {'buy_qty': 0,'product_id': 33}]

I tried with itemgetter,

sorted(total_lines, key=itemgetter('buy_qty'))

It seems to me that there might be some trick here with the "key" parameter

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3 answers


You are correct about the key function. I added a key function that sorts by buy_qty, except it is at most zero, and then treats it like infinity, essentially moving it to the end.



 sorted(values, key = lambda x: x['buy_qty'] if x['buy_qty'] > 0 else float('inf'))
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You can define any function to be used for sorting - either outside sorted

or inside using lambda. This way you can make exceptions (in this case for count 0)



 sorted(values, key=lambda x: x['buy_qty'] if x['buy_qty'] > 0 else float('Inf'))
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Use a custom compare function.

def custom_comparator(item1, item2):
    if item1 == item2:
            return 0
    elif 0 < item1 < item2 or item2 == 0:
            return -1
    else:
            return 1

 sorted(total_lines, cmp=custom_comparator, key=itemgetter('buy_qty'))
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