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How are feature_importances in RandomForestClassifier determined?
...d in [1] (often cited, but unfortunately rarely read...). It is sometimes called "gini importance" or "mean decrease impurity" and is defined as the total decrease in node impurity (weighted by the probability of reaching that node (which is approximated by the proportion of samples reaching that no...
Why do we need virtual functions in C++?
... a rat."
So far so good, right? Animals eat generic food, cats eat rats, all without virtual.
Let's change it a little now so that eat() is called via an intermediate function (a trivial function just for this example):
// This can go at the top of the main.cpp file
void func(Animal *xyz) { xyz-...
Undefined reference to `pow' and `floor'
...
Look in /lib or /usr/lib. The libraries are all named lib<name>.a or lib<name>.so - it's the "<name>" you put after the -l. In this case, the math library is named libm.so, so we call it -lm.
– ams
Dec 29 '11 at ...
Undocumented NSURLErrorDomain error codes (-1001, -1003 and -1004) using StoreKit
...
All error codes are on "CFNetwork Errors Codes References" on the documentation (link)
A small extraction for CFURL and CFURLConnection Errors:
kCFURLErrorUnknown = -998,
kCFURLErrorCancelled = -999,
kCFURLErrorBadU...
Python string class like StringBuilder in C#?
...
There is no one-to-one correlation. For a really good article please see Efficient String Concatenation in Python:
Building long strings in the Python
progamming language can sometimes
result in very slow running code. In
this article I investigate the
comp...
Why dict.get(key) instead of dict[key]?
...
It allows you to provide a default value if the key is missing:
dictionary.get("bogus", default_value)
returns default_value (whatever you choose it to be), whereas
dictionary["bogus"]
would raise a KeyError.
If omitted...
How to install Java SDK on CentOS?
I have CentOS 5, but I don't know the steps to install Java SDK on Linux.
12 Answers
...
ObservableCollection not noticing when Item in it changes (even with INotifyPropertyChanged)
...
The ContentList's Set method will not get called when you change a value inside the collection, instead you should be looking out for the CollectionChanged event firing.
public class CollectionViewModel : ViewModelBase
{
public ObservableCollection<E...
What's the $unwind operator in MongoDB?
...hat it stores your data is in the form of documents and collections, which allows for a dynamic means of adding and obtaining the data from your storage locations.
That being said, in order to understand the concept behind the $unwind parameter, you first must understand what the use case that you ...
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...d/bak/
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
yum clean all
yum makecache
如果是REHL需要修改
1.删除redhat原有的yum
rpm -aq|grep yum|xargs rpm -e --nodeps
2.下载yum安装文件
wget http://mirrors.163.com/centos/6.7/os/x86_64/Packages/yum-3.2.29-69.el6.ce...