这是一个英国的python Matlab自适应智能程序代写案例

## 1 Unsupervised learning

The aim of this report will be to summarise the work done on competitive learning in

Lab 4. You will be working with a modified version of dataset called EMNIST[1, 2]. It is

similar to the MNIST dataset with images on a grid of 28×28 pixels but with handwritten

letters instead of digits. For simplicity, the dataset has been restricted to the capital

letters A to J (i.e 10 classes) with 500 samples of each class. The format of the dataset

is the same as in the MNIST dataset, rows correspond to input patterns and columns

to attributes (or features). The provided .mat file contains an array called train images

which contains the data needed for training. Keep in mind that the EMNIST dataset is

not normalised. Please note that for educational purposes only, labels are provided. In

general, this is not the case for problems where we use unsupervised learning approaches.

Therefore your replies should not make use the labels as part of the arguments.

### 1.1 Competitive learning

Your task is to implement the standard competitive learning algorithm on a one layer

network and use it to cluster the set of hand-written letters. You may choose the number

of output units such that you can capture all 10 characters and tune the network such

that it will learn quickly and result in as few dead units as possible. To do this, you

will have to implement a method for detecting dead units among the prototypes without

visualising the weights. Please note: do not forget to normalise the weight vector and

the data at the beginning of the process.

In your report you should address the following points but are also encouraged to expand

upon these where possible:

1. Explain what is meant by unsupervised learning. What are the key ingre

dients and the objective?

2. Give a brief description of the competitive learning algorithm, including

the update rule for the network weights. Is it batch or online and what is

the difference between the two? Why is it important to normalise data and weight

vectors for competitive learning to work? What could happen otherwise? Give a

mathematical argument.

3. Give a description of the technique(s) you used to improve the training

of the network and what you achieved by using them. Provide a measure

ment of improvement (i.e. How many dead units you have on average. Perform

statistics over at least 10 different initial conditions). Include a description of your

method for identifying dead units without the need of visualising the prototypes.

4. Plot the running average of the reconstruction error as a function of

time. Change the number of output neurons and include the running

average for this on the same plot. From the lectures, the reconstruction error

for an individual sample xµ is

where k is the index of the winning neuron for that pattern and j runs over

the input neurons. An exponential running average can be updated using E¯t =

E¯t−1(1 − α) + αEt, where E¯t is the running average, α the smoothing factor and

Et the error calculated at iteration t. The first step is a boundary case and you

should set E¯0 = E0 (or t = 1 for MATLAB). When has your network sufficiently

learned from the data? How has changing the number of output neurons affected

the error? Such a curve might be more informative on semi-log or log-log axes.

5. Plot the prototypes (weight vectors) and a discuss on what they rep

resent. How many prototypes did your network find? You should reshape the

prototypes so that they are each the same shape as the input data (i.e 28 × 28)

**程序辅导定制C/C++/JAVA/安卓/PYTHON/留学生/PHP/APP开发/MATLAB**

本网站支持 Alipay WeChatPay PayPal等支付方式

**E-mail:** vipdue@outlook.com **微信号:**vipnxx

如果您使用手机请先保存二维码，微信识别。如果用电脑，直接掏出手机果断扫描。