Just add the dictionary as a dictionary object not a string :

jsobj["a"]["b"]["e"].append(dict(f=var3))

Full source :

var1 = 11
var2 = 32
jsonobj = {"a":{"b":{"c": var1,
                     "d": var2,
                     "e": [],
                    },
               },
           }
var3 = 444
jsonobj["a"]["b"]["e"].append(dict(f=var3))

jsonobj will contain :

{'a': {'b': {'c': 11, 'd': 32, 'e': [{'f': 444}]}}}

If you just want this

ips = [["custom3","modemId"],["custom3","modemId"]] 

Then all you need is a simple list comprehension

ips = [d.keys() for d in json1_obj['data']] 

If you want to actually get the values (in order), not the keys

ips = [ [ d['custom3'], d['modemId'] ]  for d in json1_obj['data']] 

Elements are added to list using append():

>>> data = {'list': [{'a':'1'}]}
>>> data['list'].append({'b':'2'})
>>> data
{'list': [{'a': '1'}, {'b': '2'}]}

If you want to add element to a specific place in a list (i.e. to the beginning), use insert() instead:

>>> data['list'].insert(0, {'b':'2'})
>>> data
{'list': [{'b': '2'}, {'a': '1'}]}

After doing that, you can assemble JSON again from dictionary you modified:

>>> json.dumps(data)
'{"list": [{"b": "2"}, {"a": "1"}]}'

When you call json.dumps() it converts the object, in this case a list of 2 elements, to a JSON formatted string. You are then taking that list of strings, and appending them to a list.

If what you are looking for is a single JSON formatted list of lists, you would want to avoid doing the json.dumps() inside the GenIdentifier object, and simply return a list from that function. Then at the end, where you do the print data, instead do print json.dumps(data)

def GenIndentifier(options):
    data=[identifier,hex_dig]
    return data

data=[]
for i in range(0,2,1):
    ...
    data.append(GenIndentifier(options))
data = json.dumps(data)
print data

This will result in the following:

[["27780741708467800000000", "f798d2cd9aec1b98fb48b34fd249fe19c06a4a1d"],
 ["27780741708467800000001", "e5073922dbb7a278769d52277d49c6ad3017b1ba"]]

When using json.dump(), you must dump the entire JSON data into the file; not just the change. Here is the code:

import json

#any number
id = 1234

with open("values.json", "r+") as file:
    data = json.load(file)
    data["filter"].append(id)
    json.dump(data, file)

import json
import ast

with open("example.json", "r") as jsonFile:
    data = json.load(jsonFile)

#data={"language": "['English', 'French']", "bank": 50}

#take a variable e

e=ast.literal_eval(data['language'])

e.append('Spanish')

data['language']=e

print(data)
#{'language': ['English', 'French', 'Spanish'], 'bank': 50}

To solve this, you need to split the input list into chunks, by 7 in your case. For this, let's use this approach. Then, use a list comprehension producing a list of dictionaries:

>>> from pprint import pprint
>>> l = [['String 1'],['String 2'],['String 3'],['String 4'],['String 5'],
... ['String 6'],['String 7'],['String 8'],['String 9'],['String 10'],
... ['String 11']]
>>> def chunks(l, n):
...     """Yield successive n-sized chunks from l."""
...     for i in range(0, len(l), n):
...         yield l[i:i+n]
... 
>>>
>>> result = [{"title%d" % (i+1): chunk[i][0] for i in range(len(chunk))} 
              for chunk in chunks(l, 7)]
>>> pprint(result)
[{'title1': 'String 1',
  'title2': 'String 2',
  'title3': 'String 3',
  'title4': 'String 4',
  'title5': 'String 5',
  'title6': 'String 6',
  'title7': 'String 7'},
 {'title1': 'String 8',
  'title2': 'String 9',
  'title3': 'String 10',
  'title4': 'String 11'}]