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Is a Python dictionary an example of a hash table?
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Yes, it is a hash mapping or hash table. You can read a description of python's dict implementation, as written by Tim Peters, here.
That's why you can't use something 'not hashable' as a dict key, like a list:
>>> a = {}
>>> b = ['some', 'list']
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Which data type for latitude and longitude?
...precision. 2 bytes for each group of 4 digits, plus 3 - 8 bytes overhead.
Read the fine manual about numeric types and geometric types.
The geometry and geography data types are provided by the additional module PostGIS and occupy one column in your table. Each occupies 32 bytes for a point. The...
Python multiprocessing PicklingError: Can't pickle
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yields an error almost identical to the one you posted:
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 505, in run
self.__target(*self.__ar...
What is the difference between old style and new style classes in Python?
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Interesting that you noticed in practice, I just read that this is because new-style classes, once they have found the attribute in the instance dict, have to do an additional lookup to work out whether it is a description, ie, it has a get method that needs to be invoked t...
How persistent is localStorage?
... local storage really serve difference purposes. Cookies are primarily for reading server-side, LocalStorage can only be read client-side. So the question is, in your app, who needs this data — the client or the server?
s...
How to store arrays in MySQL?
... you don't need relational databases, you can use e.g. a key-value store.
Read about database normalization, please. The golden rule is "[Every] non-key [attribute] must provide a fact about the key, the whole key, and nothing but the key.". An array does too much. It has multiple facts and it stor...
How to update PATH variable permanently from Windows command line?
... modifying system PATH. It just needs a simple C++ app with a few registry reads and writes, followed by a SendMessage. Set the requestedExecutionLevel to requireAdministrator in the app manifest.
– David Heffernan
Dec 2 '11 at 15:56
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How to drop columns by name in a data frame
I have a large data set and I would like to read specific columns or drop all the others.
11 Answers
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Change default timeout for mocha
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By default Mocha will read a file named test/mocha.opts that can contain command line arguments. So you could create such a file that contains:
--timeout 5000
Whenever you run Mocha at the command line, it will read this file and set a timeout ...
RESTful Login Failure: Return 401 or Custom Response
...t 401 is the proper response, I'd appreciate some explanation there. I've read the HTTP spec, as you have included here, but that to me does not read as a direct and obvious confirmation of your assertion. Namely, authentication is NOT required to ask about the validity of credentials - yet what y...