• ## The biggest difference between C + + pointer array and two-dimensional array

Time：2022-5-5

The following essay is about the description of pointer array and the biggest difference between pointer array and two-dimensional array. Pointer array The elements of the array are pointer type Example: using pointer array to store matrix 1 #include 2 using namespace std; 3 int main() { 4 int line1[] = { 1, 0, 0 […]

• ## 12.1 analysis of language differences and geo code sets Data download and sorting

Time：2022-5-3

1、 Example introduction In this section, Download gse1009 data set and use limma package for difference analysis. GSE1009   Sample size:There were 6 samples in total, of which 3 were glomerular samples of diabetes nephropathy (DN) and the other 3 were normal glomerular samples. Use chip：Affymetrix Human Genome U95 Version 2 Array。 Platform:GPL8300。 2、 Examples of […]

• ## Machine learning algorithm series (0) – basic knowledge

Time：2022-4-25

The background knowledge required for reading this article: first, lose mathematical knowledge 1、 Introduction    artificial intelligence (AI) plays a more and more important role in modern life. The support of AI is inseparable from the functions of various voice assistants, color restoration of old movies, intelligent recommendation of e-commerce websites such as Taobao Jingdong, […]

• ## Machine learning algorithm series (XII) – quadratic discriminant analysis algorithm

Time：2022-4-22

Background knowledge required for reading this article: linear discriminant analysis and yidui programming knowledge 1、 Introduction    the previous two sections introduce the implementation methods of linear discriminant analysis from different angles. One is from Fisher’s perspective of “small within class and large between classes”, and the other is from the perspective of probability distribution. […]

• ## Affine geometric transformation — opencv Python Development Guide (12)

Time：2022-4-21

affine In opencv, affine transformation refers to the translation, rotation and other operations of an image through a series of geometric transformations. The transformation can maintain the straightness and parallelism of the image. Straightness refers to that the straight line of the image is still a straight line after affine transformation; Parallelism refers to that […]

• ## R language matrix eigenvalue decomposition (spectral decomposition) and singular value decomposition (SVD) eigenvector analysis of securities data

Time：2022-4-21

Original link: http://tecdat.cn/?p=23973 R language is a very convenient data analysis language, which has built-in many methods of processing matrix. As a part of data analysis, we need to do some work on the operation of securities matrix, which only needs a few lines of code. The securities data matrix is here   D=read.table(“securite.txt”,header=TRUE) M=marix(D$,2:10$) […]

• ## Share real records | use megengine distributed communication operator to realize complex parallel training

Time：2022-4-21

In the megengine meetup on March 25th, lecturer Zhou Yizhuang of Kuangshi Research Institute shared “using megengine distributed communication operator to realize complex parallel training”. Live playback link:Using megengine’s distributed communication operator to realize complex parallel training – megengine meetup No.2_ Beeping beeping beeping beeping beeping beeping beeping beeping beeping beeping beeping beeping beeping beeping […]

• ## Machine learning algorithm series (III) – standard linear regression algorithm

Time：2022-4-20

Background knowledge required for reading this article: matrix derivation and yidui programming knowledge 1、 Introduction    two binary classification algorithms, perceptron algorithm and pocket algorithm, are introduced earlier. These algorithms solve the problem of classification, but in reality, they are more problems such as predicting the house price in a certain area, how much credit […]

• ## Epson robot basic learning notes

Time：2022-4-20

Basic concepts Axis: a movable joint that can generally do reciprocating motion or rotation. Pulse: the movement of the shaft requires a certain pulse. If there are many pulses, the movement time will be long. Origin: 0 pulse. Attitude of each axis. Point position: generally saved as (x, y, Z, U). It records the position […]

• ## 2021-07-28 logfc interpretation of limma package difference analysis results

Time：2022-4-14

First of all, we should understand that the input parameter accepted by limma is an expression matrix, and it is the expression matrix after log (with 2 as the bottom). Then, the value of the last calculated logfc column is actually the value of the average expression of case group minus the average expression of […]

• ## Machine learning algorithm series (IV) – ridge regression algorithm

Time：2022-4-12

Background knowledge required for reading this article: standard linear regression algorithm and yidui programming knowledge 1、 Introduction In the previous section, we learned the machine learning algorithm series (III) – standard linear regression algorithm, and finally obtained the analytical solution w of the cost function of standard linear regression as follows:  w=\left(X^{T} X\right)^{-1} X^{T} […]

• ## What are two-dimensional prefixes and?

Time：2022-4-12

What are prefixes and? Prefix sum is an important preprocessing, which can greatly reduce the time complexity of query. We can simply understand it as “the sum of the first n items of the sequence”. This concept is actually easy to understand, that is, in an array, the nth bit stores the sum of the […]