## Application example of PCA dimensionality reduction algorithm -- kaggle handwritten numeral recognition

preface
In the previous blog post, we learned Dimension reduction algorithm PCA , and Parameters of PCA . This article is based on the premise of having a certain foundation for PCA. This paper mainly introduces the application of PCA algorithm in practice. Including the selection of PCA parameters, the use of PCA in training set and test ...

Added by **racing_fire** on *Thu, 20 Jan 2022 00:55:16 +0200*

## Machine learning principle and practice | PCA Dimensionality Reduction Practice

%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np
1. PCA introduction
1.1 concept
Thought:
dots = np.array([[1, 1.5], [2, 1.5], [3, 3.6], [4, 3.2], [5, 5.5]])
def cross_point(x0, y0):
"""
1. line1: y = x
2. line2: y = -x + b => x = b/2
3. [x0, y0] is in line2 => b = x0 + y0
=> x1 = b/2 = ...

Added by **IanMartins** on *Tue, 14 Sep 2021 03:33:54 +0300*