R关于绘图应该可以写很多, 不过这里只列举在compstat这门课里最经常用的几个函数. 关于R的绘图, 详细了解可以运行 demo(graphics)或者 example("plot").
R里面的绘图命令分为两类: 一类是"high-level"的"创建新图片"命令, 运行以后会新画一个图 …
首先, R似乎默认所有的变量都为向量vector, 即使一个单独的数字也是长度为1的, 所以1等价于c(1).
> a <- 1
> a
[1] 1
> length(a)
[1] 1
> a[1]
[1] 1
> typeof(a)
[1] "double" # means "double vector" (I think)
> 1 == c …这个"从入门到放弃"系列是为了应付eth的computational statistics这门课... 对R无爱...
terminology
首先在stat里面有一些叫法和以前不太一样:
predictor variable: 就是机器学习里面说的feature (Xi)design points: 是机器学习里 …
4.1 - Objects Everywhere
scala is pure OO: every value is an obj, every operation is a method of obj.
scala.Int scala.Boolean maps to JVM standard primitive types.
Implement Boolean withous primitive type in scala:
Then defin false and true as objects, give implementation for ifThenElse() funciton:
object …This week, we'll cover traits, and we'll learn how to organize classes into hierarchies. We'll cover the hierarchy of standard Scala types, and see how to organize classes and traits into packages. Finally, we'll touch upon the different sorts of polymorphism in Scala.
3.1 - Class Hierarchies
abstract class
abstract …This week, we'll learn about functions as first-class values, and higher order functions. We'll also learn about Scala's syntax and how it's formally defined. Finally, we'll learn about methods, classes, and data abstraction through the design of a data structure for rational numbers.
2.1 - Higher-Order Functions
higher order functions …
In this week, we'll learn the difference between functional imperative programming. We step through the basics of Scala; covering expressions, evaluation, conditionals, functions, and recursion
1.1 - Programming Paradigms
imperative programming:
- modify mutable variables
- using assignments
- control structures: if-else, loops, break, continue, return, etc.
~~~> Von Neumann computer:
conceptualize data structures …
Get up and running with Scala on your computer. Complete an example assignment to familiarize yourself with our unique way of submitting assignments.
Tool setup
IntelliJ
use worksheet as a better REPL
SBT
navigate to the directory of the assignment you are working on, then start sbt.
(when first running …
problems with text:
- often very rare word is important, e.g. retinopathy
- ambiguity: e.g. cat and kitty
→ need a lot of labeled data ⇒ not realistic.
⇒ unsupervised learning
similar words appear in similar context.
embedding: map words to small vectors
measure the closeness by cosine distance:
word2vec
initial: random vector …
statistical invariance → weight sharing
e.g. image colors, translation invariance...
convnet
is NNs that share their weights across space.
convolution: slide a small patch of NN over the image to produce a new "image"
convnet forms a pyramid, each "stack of pincake" get larger depth and smaller area.
