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Python Data Type Q&A » dictionary » Map 

1. Map two lists into a dictionary in Python    stackoverflow.com

Imagine that you have:

keys = ('name', 'age', 'food')
values = ('Monty', 42, 'spam')
What is the simplest way to produce the following dictionary ?
dict = {'name' : 'Monty', 'age' : 42, 'food' : ...

2. Map two lists into one single list of dictionaries    stackoverflow.com

Imagine I have these python lists:

keys = ['name', 'age']
values = ['Monty', 42, 'Matt', 28, 'Frank', 33]
Is there a direct or at least a simple way to produce the following list of ...

3. Python reverse / inverse a mapping    stackoverflow.com

Given a dictionary like so:

map = { 'a': 1, 'b':2 }
How can one invert this map to get:
inv_map = { 1: 'a', 2: 'b' }

4. How do I re-map python dict keys    stackoverflow.com

I am working on a program that (among other things) reads a CSV file in (it gets stored as an array of dicts in the form [{col1:data1a,col2:data2a},{col1:data1b,col2:data2b}] ). For each row, ...

5. Mapping std::map to Python    stackoverflow.com

Sometimes it makes sense to have a key-ordered dictionary. In C++, this is often implemented with a Red-black tree. But any self-balancing binary search tree will do (fwiw, Knuth is particularly ...

6. Storing Python dictionary entries in the order they are pushed    stackoverflow.com

Fellows: A Python dictionary is stored in no particular order (mappings have no order), e.g.,

>>> myDict = {'first':'uno','second':'dos','third':'tres'}
myDict = {'first':'uno','second':'dos','third':'tres'}
>>> myDict
myDict
{'second': 'dos', 'third': 'tres', 'first': 'uno'}
While it is possible to retrieve a ...

7. Deleting key/value from list of dictionaries using lambda and map    stackoverflow.com

I have a list of dictionaries that have the same keys within eg:

[{k1:'foo', k2:'bar', k3...k4....}, {k1:'foo2', k2:'bar2', k3...k4....}, ....]
I'm trying to delete k1 from all dictionaries within the list. I tried
map(lambda x: ...

8. Map list onto dictionary    stackoverflow.com

Is there a way to map a list onto a dictionary? What I want to do is give it a function that will return the name of a key, and the ...

9. Python dictionary that maps strings to a set of strings?    stackoverflow.com

I would like to be able to make a Python dictionary with strings as keys and sets of strings as the values. E.g.: { "crackers" : ["crunchy", "salty"] } It must ...

10. The difference between python dict and tr1::unordered_map in C++    stackoverflow.com

I have a question related to understanding of how python dictionaries work. I remember reading somewhere strings in python are immutable to allow hashing, and it is the same reason why ...

11. efficient list mapping in python    stackoverflow.com

I have the following input:

input = [(dog, dog, cat, mouse), (cat, ruby, python, mouse)]
and trying to have the following output:
outputlist = [[0, 0, 1, 2], [1, 3, 4, 2]]

outputmapping = {0:dog, ...

12. reverse mapping of dictionary with Python    stackoverflow.com

If I have a dictionary named ref as follows

ref = {}
ref["abc"] = "def"
I can get "def" from "abc"
def mapper(from):
    return ref[from]
But, how can I get from "def" ...

13. Sorting list of dictionaries according to specific order    stackoverflow.com

I am using Python 2.6 and I have two data stores. Querying the first one returns a list of document IDs in a specific order. I look up all the documents ...

14. How to distinguish between a sequence and a mapping    stackoverflow.com

I would like to perform an operation on an argument based on the fact that it might be a map-like object or a sequence-like object. I understand that no strategy is ...

15. creating a dictionary that maps ascii characters using map and range    stackoverflow.com

I am having some problems with mapping characters to a dictionary. What I am going for is

counter = { '!': 0, '"': 0, '#': 0, '$': 0 } ...
For all ...

16. taking Python map package in .Net using Microsoft.samples.xmlrpc    stackoverflow.com

I have a working .net web service that is being called by a Linux client written in Python. They are sending me a map dictionary element to my method. I have ...

17. One-line expression to map dictionary to another    stackoverflow.com

I have dictionary like

d = {'user_id':1, 'user':'user1', 'group_id':3, 'group_name':'ordinary users'}
and "mapping" dictionary like:
m = {'user_id':'uid', 'group_id':'gid', 'group_name':'group'}
All i want to "replace" keys in first dictionary with keys from second (e.g. replace ...

18. Make map() return a dictionary    stackoverflow.com

I have the following function:

def heading_positions(self):
    return map(
            lambda h:
        ...

19. In Python, how can you load YAML mappings as OrderedDicts?    stackoverflow.com

I'd like to get PyYAML's loader to load mappings (and ordered mappings) into the Python 2.7+ OrderedDict type, instead of the vanilla dict and list of pairs ...

20. Omitting values from certain keys in a dict    stackoverflow.com

I am currently building a location-based service that calculates routes for users sharing cars to a specific event. In order to calculate the shortest distance, the driving distances between the users ...

21. Is dictionary in Python can be seen as Map in C++    stackoverflow.com

Is dictionary in Python can be seen as Map in C++ And the insert complexity is constant time? and what about sort complexity of dictionary? What about iteration? Need some good points or link to ...

22. map data type for python google app engine    stackoverflow.com

I would like to have a map data type for one of my entity types in my python google app engine application. I think what I need is essentially the python ...

23. Creating python lists of mapped values from keys in a list of lists    stackoverflow.com

I have a python dict as below

mymap={'java':40,'haskell':60,'ruby':50,'python':70,'scala':30,'lisp':80,'scheme':75}
I have the keys put in sublists
mapkeys = [['haskell','java'],['lisp','python'],['scala','scheme'],['ruby']]
Now,I need to create a list of lists of values of these keys as below
[[60,40],[80,70],[30,75],[50] ]
I tried ...

24. Mapping dictionary with rows values    stackoverflow.com

My problem is how to map dictionary values to row indices. I have a dictionary like:

ordered_dict = OrderedDict(1:"id", 2:"name", 3:"address", 4:"salary")
And I got rows from a select query like:
row = ["David", ...

25. Inconsistency when I'm mapping lists into a dictionary using dict and zip - Python    stackoverflow.com

I tried this example and it worked fine: Map two lists into a dictionary in Python But if I replaced "keys" with this list: ['2', '3', '2', '3', '4', '2', '4', ...

26. Inverting Dictionaries in Python    stackoverflow.com

I want to know which would be an efficient method to invert dictionaries in python. I also want to get rid of duplicate values by comparing the keys and choosing the ...

27. Python dictionary with lookup that returns an iterator    stackoverflow.com

Something I miss about C++ std::map (which is a sorted dictionary) is that looking up a key returns an iterator pointing to the correct location in the map. This means you ...

28. py3k: mapping dictionary (string->number) into list (of strings)    stackoverflow.com

Assume we have dictionary that translates strings into numbers. How to reverse it into list ? Let assume, we can fill not mapped numbers with empty string ''. Here example how it works:

>>> dic_into_list({'x':0, ...

29. Map actors and their movie onto a dictionary    stackoverflow.com

def parse_actor_data(actor_data):
    while 1:
        line = actor_data.readline().strip()
        if line.count('-') > 5:
    ...

31. Generate dictionary mapping of a folder    python-forum.org

I am searching for a way to map a folder (with all of its subfolders) in a nested dictionary, with file names and folder names as dict keys. Actually, I am trying os.walk(). However, I am not able to get the right position for the output from os.walk()... Now I wonder whether there is already a piece of code that solves ...

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