Coursera-getting and Cleaning Data-week4Thursday, January,Make up the fourth week notes, and this course summary.The four-week course focuses on text processing. Inside includes1. Handling of variable names 2. Regular Expression 3. Date processing (see Swirl lubridate package exercise)First, the processing of variable names, followed by two principles, 1) uniform case tolower/toupper;2) Remove the import data, because special characters caused by the
Coursera Andrew Ng Machine learning is really too hot, recently had time to spend 20 days (3 hours a day or so) finally finished learning all the courses, summarized as follows:(1) Suitable for getting started, speaking the comparative basis, Andrew speaks great;(2) The exercise is relatively easy, but to carefully consider each English word, or easy to make mistakes;(3) I am using MATLAB to submit the programming job, because of the MATLAB command is
Took a course on software security at Coursera. Here is a list of readings from the professor:Week 1ReadingsRequired ReadingThe only required reading this week is the following:
Common Vulnerabilities Guide for C programmers. Take note of the unsafe C library functions listed here, and how they is the source of the buffer overflow vulnerabilities. This list is relevant for the project and this week ' s quiz.
(Reference) Memory layout. Exp
IntroductionThe Machine learning section records Some of the notes I've learned about the learning process, including linear regression, logistic regression, Softmax regression, neural networks, and SVM, and the main learning data from Standford Andrew Ms Ng's tutorials in Coursera and online courses such as UFLDL Tutorial,stanford cs231n and Tutorial, as well as a large number of online related materials (listed later). PrefaceThis article mainly int
Week 1 Practice quizhelp Center
Warning:the hard deadline has passed. You can attempt it, but and you won't be. You are are welcome to try it as a learning exercise. In accordance with the Coursera Honor Code, I certify this answers here are I own work. Question 1 Consider the instantiation of the vector space model where documents and queries are represented as term Ency vectors. Assume we have the following query and two documents: Q = "Future of on
1. What is a special course (specializations)?If you want to learn a major that you do not understand, you can study according to the special course arrangement. Coursera Special Course collects a field of curriculum, and according to the Order of teaching, it is very suitable for the new people who don't feel well.2. Program Design and algorithmThis special course is a computer Foundation course published by Peking University in
(Datasets) data (IRIS)#Exploratory Analysisnames (Iris) head (IRIS)#The following attempts to take Virginica,speal. The method of length is all wrongiris[,2]iris[iris$species=="virginica", 2]mean (iris[iris$species=="virginica", 2])##the above is Error,not correct##tapply (Test$sepal.length,test$species,mean)#using Species.mean to group vectors, this method is feasible, but the above method is necessary to look at the errorLibrary (Datasets) data (Mtcars) #以下为做某个题时的若干测试. And a trial-and-error l
networks and overfitting:
The following is a "small" Neural Network (which has few parameters and is easy to be unfitted ):
It has a low computing cost.
The following is a "big" Neural Network (which has many parameters and is easy to overfit ):
It has a high computing cost. For the problem of Neural Network overfitting, it can be solved through the regularization (λ) method.
References:
Machine Learning video can be viewed or downloaded on Coursera
NTU-Coursera ml: HomeWork 1 Q15-20Question15
The training data format is as follows:
The input has four dimensions, and the output is {-1, + 1 }. There are a total of 400 data records.
The question requires that the weight vector element be initialized to 0, and then "Naive Cycle" is used to traverse the training set. When the iteration is stopped, the weight vector is updated several times.
The so-called "Naive Cycle" means that after an error i
This series is a personal learning note for Andrew Ng Machine Learning course for Coursera website (for reference only)Course URL: https://www.coursera.org/learn/machine-learning Exercise 7--k-means and PCA
Download coursera-Wunda-Machine learning-all programming practice answers
In this exercise, you will implement the K-means clustering algorithm and apply it to compressed images. In the second section, y
Operating system Learning notes----process/threading Model----Coursera Course note process/threading model 0. Overview 0.1 Process ModelMulti-Channel program designConcept of process, Process control blockProcess status and transitions, process queuesProcess Control----process creation, revocation, blocking, wake-up 、...0.2 threading ModelWhy threading is introducedThe composition of the threadImplementation of threading mechanismUser-level threads, c
full implementation of multi-layered neural network recognition picture of the cat Original Coursera Course homepage, in the NetEase cloud classroom also has the curriculum resources but no programming practice. This program uses the functions completed in the last job, fully implementing a multilayer neural network, and training to identify whether there is a cat in the picture. There is no comment in the Code and Training test data download Cod
We recommend the responsive programming course on Coursera, an advanced Scala language course. At the beginning of the course, we proposed an Application Scenario: constructing a JSON string. If you do not know the JSON string, you can simply Google it. To do this, we define the following classes
abstract class JSON case class JSeq(elems: List[JSON]) extends JSON case class JObj(bindings: Map[String, JSON]) extends JSON case class JNum(num: Double) e
#include using namespacestd;/*int Wanmeifugai (int n) {if (n%2) {return 0; } else if (n==2) {return 3; }else if (n = = 0) return 1; else return (3*3) *wanmeifugai (n-4);}*///The following is a reference to the online program/*Ideas: Citation:http://m.blog.csdn.net/blog/njukingway/20451825First: F (n) = 3*f (n-2) + ... f (n) = 3*f (n-2) + 2*f (n-4) +....//just now our recursion is pushed in the smallest unit (3 blocks), but there are large units of small units (6, 9, 12 blocks, etc.) There
Week 2 gradient descent for multiple variables
[1] multi-variable linear model cost function
Answer: AB
[2] feature scaling feature Scaling
Answer: d
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[Original] Andrew Ng chose to fill in the blanks in Coursera for Stanford machine learning.
m>=10n and uses multiple Gaussian distributions.In practical applications, the original model is more commonly used, the average person will manually add additional variables.If the σ matrix is found to be irreversible in practical applications, there are 2 possible reasons for this:1. The condition of M greater than N is not satisfied.2. There are redundant variables (at least 2 variables are exactly the same, XI=XJ,XK=XI+XJ). is actually caused by the linear correlation of the characteristic
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