Function that transforms a list in a list of dictionary

Question

I have to make a function whose purpose is taking in parameter a list.

Such as this one :

['music', ' extension=mp3', 'reports/INFOB131', ' extension=doc,docx,pdf', ' name_contains=INFOB131', ' max_size=100000', 'reports/INFOB132', ' extension=doc,docx,pdf', ' name_contains=INFOB132', ' max_size=100000', 'games', ' name_contains=SC2,Wesnoth', 'pictures/Namur', ' extension=jpeg', ' min_size=5000000', ' name_contains=cercle', 'pictures/autres', ' extension=jpeg', ' min_size=5000000']

And return a list similar to this :

data_config = [{'music' : {'extension':'mp3'}}, {'reports/INFOB131': {'extension': ['doc', 'docx','pdf'], 'name_contains':'INFOB131', 'max_size':100000}}, {'reports/INFOB132': {'extension': ['doc', 'docx','pdf'], 'name_contains':'INFOB132', 'max_size':100000}}]

So I made that function :

def my_function(list_in_question, my_config_list =[], prev_list = []):
    """ """
    enumerated_list = list(enumerate(list_in_question))

    if not '=' in enumerated_list[0][1]:
        main_key = enumerated_list[0][1]# référencé avant assignement
        pre_dict = {main_key : {}}


        for i in enumerated_list[1:]:

            if '=' in i[1] :
                splitted = i[1].split('=')
                prev_list.append({splitted[0] : splitted[1]})

            elif not '=' in i[1] and i[1] != main_key:
                for j in prev_list:
                    pre_dict[main_key].update(j)

                my_config_list.append(pre_dict)

                return my_function(list_in_question[i[0]:])

            elif not '=' in i[1] and i[1] == main_key and main_key!= enumerated_list[0][1]:
                return my_config_list
    else:
        print("The format of the file containig the data in not adequate !")

But I don't understand why when I execute it this way :

new_lines = ['music', ' extension=mp3', '', 'reports/INFOB131', ' extension=doc,docx,pdf', ' name_contains=INFOB131', ' max_size=100000', '', 'reports/INFOB132', ' extension=doc,docx,pdf', ' name_contains=INFOB132', ' max_size=100000', '', 'games', ' name_contains=SC2,Wesnoth', '', 'pictures/Namur', ' extension=jpeg', ' min_size=5000000', ' name_contains=cercle', '', 'pictures/autres', ' extension=jpeg', ' min_size=5000000']

my_function(new_lines)

I end up with this output...

None

I would be very grateful if someone could help me,

Thank you !

PS : If anyone have an idea of how I could do without loop and do it in a recursive way, it would be awesome !

Everyone... Thank you !!! You really hepled me, all your answers are awesome, I have some issues to understand some parts so I'll be annoying just a little longer with some questions of you code. Anyway, thank you for the time you took to help me, you were all more than great help !!!

Finish your function with a `return my_config_list` to, well, return the list. — Mr. T, Dec 05 '17 at 08:37

aprasanth · Accepted Answer · 2017-12-06T06:03:03.463

Try the following code;

def foo(my_list):
    # Create an iterator
    list_iter = iter(my_list)
    # zip the iterator with itself
    key_val_tuple = zip(list_iter, list_iter) # This will group two items in the list at a time
    output_list = []
    for i in key_val_tuple:
        value_dict = {}
        value = i[1].split('=')
        value_dict[value[0]] = value[1].split(",") if len(value[1].split(","))>1 else value[1]
        element_dict = {}
        element_dict[i[0]] = value_dict
        output_list.append(element_dict)
    return output_list

input_list = ['music', ' extension=mp3', 'reports/INFOB131', ' extension=doc,docx,pdf', ' name_contains=INFOB131', ' max_size=100000', 'reports/INFOB132', ' extension=doc,docx,pdf', ' name_contains=INFOB132', ' max_size=100000', 'games', ' name_contains=SC2,Wesnoth', 'pictures/Namur', ' extension=jpeg', ' min_size=5000000', ' name_contains=cercle', 'pictures/autres', ' extension=jpeg', ' min_size=5000000']

# Call the function foo
output = foo(input_list)
print(output) # python3

Got the following output

[{'music': {' extension': 'mp3'}}, {'reports/INFOB131': {' extension': ['doc', 'docx', 'pdf']}}, {' name_contains=INFOB131': {' max_size': '100000'}}, {'reports/INFOB132': {' extension': ['doc', 'docx', 'pdf']}}, {' name_contains=INFOB132': {' max_size': '100000'}}, {'games': {' name_contains': ['SC2', 'Wesnoth']}}, {'pictures/Namur': {' extension': 'jpeg'}}, {' min_size=5000000': {' name_contains': 'cercle'}}, {'pictures/autres': {' extension': 'jpeg'}}]

zip(list_iter, list_iter) : This will group two items in the list at a time.

output : [('music', ' extension=mp3'), ('reports/INFOB131', ' extension=doc,docx,pdf'), ...]

Reference:

Thank you so much ! It worked perfectly !!! Just a question, could you explain me the use of the zip() and iter() ? — Manoa, Dec 05 '17 at 14:36
Please see the updated answer with proper comments and reference links. Let me know if you have any doubts still.. — aprasanth, Dec 06 '17 at 06:04

score 1 · Answer 2 · answered Dec 05 '17 at 09:19

You need to traverse the list one time. The pattern is this:

Start an empty list (let's call it new_list)
You find an element in the original list (original_list).
If it does not contain '=', you create a new dictionary in the new_list

If it contains the '=' sign, split the element into k and v (before and after the '='), and in the last entry in the new_list, for the only key, you add a key-value pair

def parse_list(original_list):
    new_list=[]

    for element in original_list:
        if not '=' in element:
            new_list.append({element:{}})
        else:
            k,w=element.split('=')
            new_list[-1][new_list[-1].keys()[0]][k]=w
    return new_list

new_lines = ['music', ' extension=mp3', '', 'reports/INFOB131', ' extension=doc,docx,pdf', ' name_contains=INFOB131', ' max_size=100000', '', 'reports/INFOB132', ' extension=doc,docx,pdf', ' name_contains=INFOB132', ' max_size=100000', '', 'games', ' name_contains=SC2,Wesnoth', '', 'pictures/Namur', ' extension=jpeg', ' min_size=5000000', ' name_contains=cercle', '', 'pictures/autres', ' extension=jpeg', ' min_size=5000000']

parse_list(new_lines)

Now I should explain the line before the return statement:

new_list[-1] is the dictionary corresponding to the last entry without an equal sign that was found in the original_list. After the first pass through the loop,

new_list=[{'music': {}}]
during the second pass

new_list[-1]={'music': {}}

new_list[-1].keys()=['music']

new_list[-1].keys()[0]='music'

new_list[-1][new_list[-1].keys()[0]]={}
now you just update this dictionary with the parsed k,w pair

thank you for your help, if you could just help me to understand this line : new_list[-1][new_list[-1].keys()[0]][k]=w , why [-1] and what does .keys() do ? — Manoa, Dec 05 '17 at 14:59
[-1] is the index of the last element in a list. somelist[-1] the same as somelist[len(somelist)-1]. The keys() function return the keys from the dictionary. {'extension': ['doc', 'docx','pdf'], 'name_contains':'INFOB131', 'max_size':100000}.keys() should return ['max_size', 'name_contains', 'extension']. I know that you main dictionaries contain only one key word (for example 'music') so I grabbed the first (and only) element in that list, so I can access the value (the dictionary with all other key-value pairs) — Andrei, Dec 05 '17 at 16:35

B. M. · Answer 3 · 2017-12-05T09:48:02.160

Yet another try with only lists and dicts:

def make(lst):
    data_config=[]
    for st in lst:
        if '=' not in st:            # new entry
            dd = dict()
            dds = dd[st] = dict()
            data_config.append(dd)            
        else:                        # fill entry
            k,v = st.split('=')
            if ',' in v:
                v = v.split(',')
            dds[k] = v          
    return data_config

For :

In [564]: make(l)
Out[564]: 
[{'music': {' extension': 'mp3'}},
 {'reports/INFOB131': {' extension': ['doc', 'docx', 'pdf'],
   ' max_size': '100000',
   ' name_contains': 'INFOB131'}},
 {'reports/INFOB132': {' extension': ['doc', 'docx', 'pdf'],
   ' max_size': '100000',
   ' name_contains': 'INFOB132'}},
 {'games': {' name_contains': ['SC2', 'Wesnoth']}},
 {'pictures/Namur': {' extension': 'jpeg',
   ' min_size': '5000000',
   ' name_contains': 'cercle'}},
 {'pictures/autres': {' extension': 'jpeg', ' min_size': '5000000'}}]

Awesome and easily understandable ! I'm a beginner so this seems perfect to me ! — Manoa, Dec 05 '17 at 15:28

score 1 · Answer 4 · answered Dec 05 '17 at 09:41

One more way of doing it:

import re

def my_function(list_in_question, my_config_list=[], prev_list=[]):
    """ """
    result = {}
    main_key = ''

    for element in list_in_question:
        if element == '':
            main_key = ''
        if re.search('=', element):
            key, value = element.split('=')
            print "key, value = ", key, value
            if re.search(',', value):
                value_list = value.split(',')
                print "value list =", value_list
                result[main_key][key] = value_list
            else:
                result[main_key][key] = value

        else:
            main_key = element
            result[main_key] = {}

    return (result)

new_lines = ['music', ' extension=mp3', '', 'reports/INFOB131', ' extension=doc,docx,pdf', ' name_contains=INFOB131',
             ' max_size=100000', '', 'reports/INFOB132', ' extension=doc,docx,pdf', ' name_contains=INFOB132',
             ' max_size=100000', '', 'games', ' name_contains=SC2,Wesnoth', '', 'pictures/Namur', ' extension=jpeg',
             ' min_size=5000000', ' name_contains=cercle', '', 'pictures/autres', ' extension=jpeg',
             ' min_size=5000000']

print (my_function(new_lines))

Thank you for your help, the code works the only issue I encountered is that I get the code in this order : — Manoa, Dec 05 '17 at 15:26
{'games': {' name_contains': ['SC2', 'Wesnoth']}, 'music': {' extension': 'mp3'}, 'pictures/Namur': {' extension': 'jpeg', ' min_size': '5000000', ' name_contains': 'cercle'}, 'pictures/autres': {' extension': 'jpeg', ' min_size': '5000000'}, 'reports/INFOB131': {' extension': ['doc', 'docx', 'pdf'], ' max_size': '100000', ' name_contains': 'INFOB131'}, 'reports/INFOB132': {' extension': ['doc', 'docx', 'pdf'], ' max_size': '100000', ' name_contains': 'INFOB132'}} — Manoa, Dec 05 '17 at 15:27

Function that transforms a list in a list of dictionary

4 Answers4