October 2021
Intermediate to advanced
289 pages
8h 31m
Chinese
Content preview from 数据科学中的实用统计学(第2版)
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
统计机器学习
｜
201
sklearn.preprocessing.StandardScaler
方法先使用预测变量进行训练，然后在训练
KNN
模型之前转换数据集：
newloan = loan_data.loc[0:0, predictors]
X = loan_data.loc[1:, predictors]
y = loan_data.loc[1:, outcome]
scaler = preprocessing.StandardScaler()
scaler.fit(X * 1.0)
X_std = scaler.transform(X * 1.0)
newloan_std = scaler.transform(newloan * 1.0)
knn = KNeighborsClassifier(n_neighbors=5)
knn.fit(X_std, y)
nbrs = knn.kneighbors(newloan_std)
X.iloc[nbrs[1][0], :]
5
个最近邻在所有变量上都更加相似，这是一个更有意义的结果。请注意，展示结果时使
用的是初始数据，但在应用
KNN
方法时，使用的是缩放后的数据和要预测的新贷款数据。
使用
z
分数只是对变量进行重缩放的方法之一。除了均值，还可以使用更加
健壮的位置估计，比如中位数。类似地，也可以使用不同的范围估计来替代
标准差，比如四分位距。有时候，变量要被“挤压”到
0
和
1
之
间。还需要
注意的是，将所有变量都缩放到单位方差有时候过于武断，因为这意味着我
们认为每个变量在预测效能方面的重要性是一样的 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.