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How to create a nested python dictionary with keys as strings?

Summary of issue: I'm trying to create a nested Python dictionary, with keys defined by pre-defined variables and strings. And I'm populating the dictionary from regular expressions outputs. This mostly works. But I'm getting an error because the nested dictionary - not the main one - doesn't like having the key set to a string, it wants an integer. This is confusing me. So I'd like to ask you guys how I can get a nested python dictionary with string keys.
Below I'll walk you through the steps of what I've done. What is working, and what isn't. Starting from the top:
# Regular expressions module
import re
# Read text data from a file
file = open("dt.cc", "r")
dtcc = file.read()
# Create a list of stations from regular expression matches
stations = sorted(set(re.findall(r"\n(\w+)\s", dtcc)))
The result is good, and is as something like this:
stations = ['AAAA','BBBB','CCCC','DDDD']
# Initialize a new dictionary
rows = {}
# Loop over each station in the station list, and start populating
for station in stations:
rows[station] = re.findall("%s\s(.+)" %station, dtcc)
The result is good, and is something like this:
rows['AAAA'] = ['AAAA 0.1132 0.32 P',...]
However, when I try to create a sub-dictionary with a string key:
for station in stations:
rows[station] = re.findall("%s\s(.+)" %station, dtcc)
rows[station]["dt"] = re.findall("%s\s(\S+)" %station, dtcc)
I get the following error.
"TypeError: list indices must be integers, not str"
It doesn't seem to like that I'm specifying the second dictionary key as "dt". If I give it a number instead, it works just fine. But then my dictionary key name is a number, which isn't very descriptive.
Any thoughts on how to get this working?

The issue is that by doing
rows[station] = re.findall(...)
You are creating a dictionary with the station names as keys and the return value of re.findall method as values, which happen to be lists. So by calling them again by
rows[station]["dt"] = re.findall(...)
on the LHS row[station] is a list that is indexed by integers, which is what the TypeError is complaining about. You could do rows[station][0] for example, you would get the first match from the regex. You said you want a nested dictionary. You could do
rows[station] = dict()
rows[station]["dt"] = re.findall(...)
To make it a bit nicer, a data structure that you could use instead is a defaultdict from the collections module.
The defaultdict is a dictionary that accepts a default type as a type for its values. You enter the type constructor as its argument. For example dictlist = defaultdict(list) defines a dictionary that has as values lists! Then immediately doing dictlist[key].append(item1) is legal as the list is automatically created when setting the key.
In your case you could do
from collections import defaultdict
rows = defaultdict(dict)
for station in stations:
rows[station]["bulk"] = re.findall("%s\s(.+)" %station, dtcc)
rows[station]["dt"] = re.findall("%s\s(\S+)" %station, dtcc)
Where you have to assign the first regex result to a new key, "bulk" here but you can call it whatever you like. Hope this helps.

Sorting a list of dict from redis in python

in my current project i generate a list of data, each entry is from a key in redis in a special DB where only one type of key exist.
r = redis.StrictRedis(host=settings.REDIS_AD, port=settings.REDIS_PORT, db='14')
item_list = []
keys = r.keys('*')
for key in keys:
item = r.hgetall(key)
item_list.append(item)
newlist = sorted(item_list, key=operator.itemgetter('Id'))
The code above let me retrieve the data, create a list of dict each containing the information of an entry, problem is i would like to be able to sort them by ID, so they come out in order when displayed on my html tab in the template, but the sorted function doesn't seem to work since the table isn't sorted.
Any idea why the sorted line doesn't work ? i suppose i'm missing something to make it work but i can't find what.
EDIT :
Thanks to the answer in the comments,the problem was that my 'Id' come out of redis as a string and needed to be casted as int to be sorted
key=lambda d: int(d['Id'])

All values returned from redis are apparently strings and strings do not sort numerically ("10" < "2" == True).
Therefore you need to cast it to a numerical value, probably to int (since they seem to be IDs):
newlist = sorted(item_list, key=lambda d: int(d['Id']))

Python:Get value of a dictionary present in aTuple

I have a tuple like: t= ({'count': 5L},)
Here i don't want to use for loop but want to get value as 5.Then how can i do it?
I tried with coverting to string then using JSON.
import json
s = str(t)
d = json.loads(s)
I got error:ValueError: No JSON object could be decoded
And winded up with no result.
I want to get the value of count as integer 5 & store in a variable.
Anyone having any idea?

No need to use Json since it is already your tuple is already a Python data structure.
If you know the index of the item in the tuple, and you know the keyname you can access it directly using:
t = ({'count': 5L},)
value = int(t[0]['count'])

Adding keys with empty values and then adding values in a nested format in python

I am trying to create and add elements to a dictionary in the following format,
{{"source1": { "destination11": ["datetime1", "datetime2", ....]}
{ "destination12": ["datetime3", "datetime4",....]}
........................................
}
{"source2": { "destination21": ["datetime5", "datetime6", ....]}
{ "destination22": ["datetime7", "datetime8",....]}
.......................................
}
.........................................}
All the keys and values are variables which I am getting from other modules.
I have created an empty dictionary
call_record=[{}]
To add the "source1", "source2" as keys I tried,
call_record.append({source1 :})
Now i can't add a value to this key yet because i will be adding it in the next lines, so I need to create this key with empty value and then add values as I get them from the next modules. But, this line doesn't create a key with empty value.
Besides, to add "destination11", "destination12"ets, I tried,
call_record[i].append(destination11)
But, this doesn't add the destinations as the values of the source key.
I have to add the datetimes, after I have added the destinations. Then I have to dump this dictionary in a json file.

.append is used to add an element to an array.
The correct sintax to add an element to a dictionary is your_dictionary[key] = value
In your case you can pass the arguments to your dictionary as follow:
import json
call_record = {} # To create an empty dictionary
call_record["source1"] = {} # To append an empty dictionary to the key "source1"
call_record["source1"]["destination11"] = [] # An empty array as value for "destination11"
call_record["source1"]["destination11"].append("datetime1", "datetime2") # To append element datetime1 and datetime2 to destination11 array
call_record_json = json.dumps(call_record, ensure_ascii=False)
I would however suggest to have a look at the python documentation to clarify the data structure in python.
You can also refer to JSON encoder and decoder section of the documentation for further examples about how to use it.

Adding Multiple Values to a Single Key in Python Dictionary

Python dictionaries really have me today. I've been pouring over stack, trying to find a way to do a simple append of a new value to an existing key in a python dictionary adn I'm failing at every attempt and using the same syntaxes I see on here.
This is what i am trying to do:
#cursor seach a xls file
definitionQuery_Dict = {}
for row in arcpy.SearchCursor(xls):
# set some source paths from strings in the xls file
dataSourcePath = str(row.getValue("workspace_path")) + "\\" + str(row.getValue("dataSource"))
dataSource = row.getValue("dataSource")
# add items to dictionary. The keys are the dayasource table and the values will be definition (SQL) queries. First test is to see if a defintion query exists in the row and if it does, we want to add the key,value pair to a dictionary.
if row.getValue("Definition_Query") <> None:
# if key already exists, then append a new value to the value list
if row.getValue("dataSource") in definitionQuery_Dict:
definitionQuery_Dict[row.getValue("dataSource")].append(row.getValue("Definition_Query"))
else:
# otherwise, add a new key, value pair
definitionQuery_Dict[row.getValue("dataSource")] = row.getValue("Definition_Query")
I get an attribute error:
AttributeError: 'unicode' object has no attribute 'append'
But I believe I am doing the same as the answer provided here
I've tried various other methods with no luck with various other error messages. i know this is probably simple and maybe I couldn't find the right source on the web, but I'm stuck. Anyone care to help?
Thanks,
Mike

The issue is that you're originally setting the value to be a string (ie the result of row.getValue) but then trying to append it if it already exists. You need to set the original value to a list containing a single string. Change the last line to this:
definitionQuery_Dict[row.getValue("dataSource")] = [row.getValue("Definition_Query")]
(notice the brackets round the value).
ndpu has a good point with the use of defaultdict: but if you're using that, you should always do append - ie replace the whole if/else statement with the append you're currently doing in the if clause.

Your dictionary has keys and values. If you want to add to the values as you go, then each value has to be a type that can be extended/expanded, like a list or another dictionary. Currently each value in your dictionary is a string, where what you want instead is a list containing strings. If you use lists, you can do something like:
mydict = {}
records = [('a', 2), ('b', 3), ('a', 4)]
for key, data in records:
# If this is a new key, create a list to store
# the values
if not key in mydict:
mydict[key] = []
mydict[key].append(data)
Output:
mydict
Out[4]: {'a': [2, 4], 'b': [3]}
Note that even though 'b' only has one value, that single value still has to be put in a list, so that it can be added to later on.

Use collections.defaultdict:
from collections import defaultdict
definitionQuery_Dict = defaultdict(list)
# ...