Implement a group_by_owners dictionary

I personally found the upvoted answer hard to understand and some others a bit bulky. Here is my version:

def group_by_owners(files):

ownerdict = {}

for key, value in files.items():
    if value in ownerdict:
        ownerdict[value].append(key)
    else:
        ownerdict[value] = [key]
return ownerdict


files = {
    'Input.txt': 'Randy',
    'Code.py': 'Stan',
    'Output.txt': 'Randy'
}
print(group_by_owners(files))

This worked for me. I believe this would be more efficient and simpler one.

# Input dictionary.
files = {
        'Input.txt': 'Randy',
        'Code.py': 'Stan',
        'Output.txt': 'Randy'
    }   
# Function to group the files.   
def group_by_owners(files):

    # Dictionary object to hold the result.
    result = {}

    for key, value in files.items():

        if value not in result.keys():

            # Insert the values into the resulting dictionary
            # by interchanging the key, values.
            result[value] = [key]
        else:

            # Append the othet file name if the owner is same.
            result[value].append(key)

    return result

print(group_by_owners(files))

Here is the output:

{'Randy': ['Input.txt', 'Output.txt'], 'Stan': ['Code.py']}

I just started learning and I am a noob at python too but used 2.7. So spare me the parentheses for prints.

I like your idea of dummy list and append. Something similar but may be a little cleaner:

files = {
    'Input.txt': 'Randy',
    'Code.py': 'Stan',
    'Output.txt': 'Randy'
}
owners=[]
filenames=files.keys()
for key in files:
    if files[key] not in owners:
        owners.append(files[key])
print owners
print filenames

result={}
for i in owners:
    resultvalues=[]
    for key in files:
        if files[key]==i: 
            resultvalues.append(key)
            print resultvalues
            result[i]=resultvalues
print result

here I mentioning easily understandable solution,

owner = []
for i in dict1.keys():
if j not in owner:
    owner.append(j)
results = {}
for i in owner:
    result = []
    for j in dict1.keys():
        if dict1.get(j) == i:
            result.append(j)
        results[i] = result
print results

def group_by_owners(files):    
    values = []
    dic = {}

    for k,v in files.items():
        values.append(v)

    s_values = set(values)
    l_values = list(s_values)

    for i in l_values:
        keys=[] 
        for k,v in files.items():
            if v == i:
             keys.append(k)
        dic[i]=keys            

    return dic

You all seems better I took 3.5 hours to get answer with lot of try and error as am new to python and weak in thinking focused, thanks to @zwer for teaching something new.

dic={'apple':['green','red'], 'power': ['voltage'],'banana': ['green','red'],'current':['voltage'],'grass':['green'],'tiger':['lion']}


i = 0
adic = {}
while i < len(dic):
    key = list(dic)[i]
    for key2 in list(dic):
        if key2 != key:
            j = 0
            while j < len(dic[key]):
                if dic[key][j] in dic[key2]:
                    color = dic[key][j]
                    if dic[key][j] in adic:
                        if key not in adic[color]:
                            adic[dic[key][j]].append(key)

                    else:
                        mdic = {dic[key][j]: [key]}
                        adic.update(mdic)
                else:
                    if dic[key][j] not in adic:
                        mdic = {dic[key][j]: [key]}
                        adic.update(mdic)
                j = j + 1
    i = i + 1
print(adic)

class FileOwners:
    def group_by_owners(files):
    temp=[]

    for i in files:
        if files[i] not in temp:
            temp.append (files[i])
        result={}

    for j in temp:
        temp1=[]
        for i in files:
            if files[i]==j: 
                temp1.append(i)
                result[j]=temp1
    return (result)

files = {'Input.txt': 'Randy',
        'Code.py': 'Stan',
        'Output.txt': 'Randy'}

print(FileOwners.group_by_owners(files))

You have to iterate Dictionary into Dictionary and compare values and append keys in a new list. Take output in a new Dictionary.

class FileOwners:

    @staticmethod

    def group_by_owners(files):
        new_dic = {}

        for key,val in files.items():
            key_list = []
            for k,v in files.items():

                if v == val:
                    #print(v)
                    key_list.append(k)
                    new_dic[v]= key_list

        return new_dic
        #print(new_dic)
files = {
    'Input.txt': 'Randy',
    'Code.py': 'Stan',
    'Output.txt': 'Randy'
}
print(FileOwners.group_by_owners(files))

I made a dict of owners and their associated list of filenames. To do that i firstly created the dictionary with the values of the passed dictionary files as keys and empty list as values. Then looped through files and appended the empty list with the keys of files

def group_by_owners(files):
    return_dict = {}
    owner_files = files.keys()
    for f in owner_files:
        return_dict[files[f]] = []
    for f, n in files.items():
        return_dict[n].append(f)
    return return_dict

I started learning Python yesterday and came across this question on testdome. Here's my answer :

def group_by_owners(files):
    f = files.values()
    s = set(f)
    newdict={}
    fileOwners = list(s)
    for owner in fileOwners:
        l=[]
        for file in files:
            if owner == files[file]:
                l.append(file)
        newdict[owner]=l
    return newdict


files = {
    'Input.txt': 'Randy',
    'Code.py': 'Stan',
    'Output.txt': 'Randy'
}   
print(group_by_owners(files))

1. This is some complex code to understand.

2. but is one of the solutions.

       files={
         'input.txt':'randy',
         'output.txt':'randy',
         'code.py':'stan'
         }
     k=files.keys()
     newfiles={value:key for key,value in files.items()}
     emptylist=[]
     for key in k:
         if key not in newfiles.values():
             missfile=key
             valuetoadd=files[missfile]
     emptylist.append(newfiles[valuetoadd])
     emptylist.append(missfile)
     newfiles[valuetoadd]=emptylist
     print(newfiles)
   

Here is my answer with defaultdict:

    from collections import defaultdict
    
    d = defaultdict(list)

    def group_by_owners(files):
        for k,v in files.items():
            d[v].append(k)
        return dict(d.items())

    if __name__ == "__main__":    
        files = {
            'Input.txt': 'Randy',
            'Code.py': 'Stan',
            'Output.txt': 'Randy'
        }   
        print(group_by_owners(files))