＠property 是 Obj-C 2.0 版開始提供的一種功能，目的是要簡化一個 instance variable 的設定過程。
instance variable (以下簡稱 ivar ) 在 Obj-C 裡預設為 protected ， 代表只有這個 class or 它的 subclass 可以 access 值。 如果這個 ivar 要給外部使用的話，那就必須必須加上 public 的 method setter/getter。 然而，每宣告一個要給外部使用的 ivar 就要宣告一組 setter/getter 太麻煩，因此 Obj-C 加入了 @property 的語法 。
舉例來說，原本想讓外部的人使用 weight 要這樣寫：
| import numpy as np | |
| from sklearn.ensemble import EnsembleSelectionClassifier | |
| from sklearn import datasets | |
| from sklearn.tree import DecisionTreeClassifier | |
| from sklearn.ensemble import AdaBoostClassifier | |
| from sklearn.linear_model import LogisticRegression | |
| from sklearn.svm import SVC | |
| from sklearn import cross_validation | |
| from sklearn.metrics import accuracy_score | |
| import sklearn.preprocessing as preprocessing |
public static class TokenizerMapper
extends Mapper<Object, Text, NullWritable, LongWritable>{
private TreeMap<Long, String> numbers = new TreeMap<Long, String>();
import numpy as np
from scipy import sparse as sp
from sklearn.datasets.samples_generator import make_blobs
from csr_row_norms import csr_row_norms
import timeit
centers = np.array([
[0.0, 5.0, 0.0, 0.0, 0.0],
[1.0, 1.0, 4.0, 0.0, 0.0],
In case you don't know, HTTP is stateless, which means the server you are communicating will not know who you are or what you've said to it before.
Say you logged in to a website, you will notice that you don't need to type your username, password etc when you visit the site again.
It looks like the server knows who you are, how could this be possible?
That's because a "session" is handling this for you.
Remember that HTTP is stateless, which means the server has no memories about what it said or what it heard.