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How to use filter, map, and reduce in Python 3
...ou can read about the changes in What's New In Python 3.0. You should read it thoroughly when you move from 2.x to 3.x since a lot has been changed.
The whole answer here are quotes from the documentation.
Views And Iterators Instead Of Lists
Some well-known APIs no longer return lists:
[...]
map(...
Python “raise from” usage
...and the message states that the exception was directly caused by. If you omit the from then no __cause__ is set, but the __context__ attribute may be set as well, and the traceback then shows the context as during handling something else happened.
Setting the __context__ happens if you used raise i...
Fatal error: “No Target Architecture” in Visual Studio
When I try to compile my c++ project using Visual Studio 2010 in either Win32 or x64 mode I get the following error:
11 Ans...
How can I implement a tree in Python?
...an/Jan'), Node('/Udo/Dan/Joe'))
Features
anytree has also a powerful API with:
simple tree creation
simple tree modification
pre-order tree iteration
post-order tree iteration
resolve relative and absolute node paths
walking from one node to an other.
tree rendering (see example above)
node attach...
C# 5 async CTP: why is internal “state” set to 0 in generated code before EndAwait call?
...articular delving into what the generated code looked like, and the GetAwaiter() / BeginAwait() / EndAwait() calls.
4...
Calling constructors in c++ without new
...ng a constructor of the format Thing(const char*).
The second one is a bit more complex. It essentially does the following
Create an object of type Thing using the constructor Thing(const char*)
Create an object of type Thing using the constructor Thing(const Thing&)
Call ~Thing() on the o...
How to find out which package version is loaded in R?
I am in a process of figuring out how to use my university cluster. It has 2 versions of R installed. System wide R 2.11 (Debian 6.0) and R 2.14.2 in non-standard location.
...
Why does Ruby 1.9.2 remove “.” from LOAD_PATH, and what's the alternative?
...
It was deemed a "security" risk.
You can get around it by using absolute paths
File.expand_path(__FILE__) et al
or doing
require './filename' (ironically).
or by using
require_relative 'filename'
or adding an "inc...
Is it possible to forward-declare a function in Python?
Is it possible to forward-declare a function in Python? I want to sort a list using my own cmp function before it is declared.
...
Get model's fields in Django
Given a Django model, I'm trying to list all of its fields. I've seen some examples of doing this using the _meta model attribute, but doesn't the underscore in front of meta indicate that the _meta attribute is a private attribute and shouldn't be accessed directly? ... Because, for example, the ...