Sort list of dictionaries according to custom ordering-CodePudding

I need to sort list of dictionaries according to predefined list of values

I am using this part of code, and it will work fine but l_of_dicts has values which are not in a sort_l(predefined list of values)

l_of_dicts = [{'name':'Max','years':18},{'name':'John','years':25},{'name':'Ana','years':19},{'name':'Melis','years':38},{'name':'Ivana','years':38}]

sort_l = ['Ana','Melis','John','Max','Peter']

res = sorted(l_of_dicts , key = lambda ele: sort_l .index(list(ele.values())[0]))

I get an error :

ValueError: 'Ivana' is not in list

Is it posible to ignore that values? or even better extract them to another list?

CodePudding user response：

The script bellow does the job but looks heavier than it should be. Maybe there's easier way to do it.

Script:

def sort_dict_list(dict_list, sorting_list):
    result = []
    not_used_values = []
    temp = {}
    for index, dictionary in enumerate(dict_list):
        temp[dictionary['name']] = index
    for item in sorting_list:
        if item in temp.keys():
            result.append(dict_list[temp[item]])
        else:
            not_used_values.append(item)
    return result, not_used_values

CodePudding user response：

You could do some preprocessing to store the ordering of only names in l_of_dicts:

l_of_dicts = [{'name': 'Max', 'years': 18}, {'name': 'John', 'years': 25},
              {'name': 'Ana', 'years': 19}, {'name': 'Melis', 'years': 38}]
names_in_dicts = {d['name'] for d in l_of_dicts if 'name' in d}
sort_l = ['Ana', 'Melis', 'Ivana', 'John', 'Max', 'Peter']
sort_order = {name: order for order, name in enumerate(sort_l) if name in
              names_in_dicts}
print(sort_order)  # {'Ana': 0, 'Melis': 1, 'John': 3, 'Max': 4}
sorted_l_of_dicts = sorted(l_of_dicts, key=lambda d: sort_order[d['name']])
print(sorted_l_of_dicts)  # [{'name': 'Ana', 'years': 19}, {'name': 'Melis', 'years': 38}, {'name': 'John', 'years': 25}, {'name': 'Max', 'years': 18}]