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0. 从RNN说起

循环神经网络(Recurrent Neural Network,RNN)是一种用于处理序列数据的神经网络。相比一般的神经网络来说,他能够处理序列变化的数据。比如某个单词的意思会因为上文提到的内容不同而有不同的含义,RNN就能够很好地解决这类问题。

转自知乎陈诚专栏

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卡尔曼滤波(Kalman filter)是一种高效的自回归滤波器,它能在存在诸多不确定性情况的组合信息中估计动态系统的状态,是一种强大的、通用性极强的工具。它的提出者,鲁道夫.E.卡尔曼,在一次访问NASA埃姆斯研究中心时,发现这种方法能帮助解决阿波罗计划的轨道预测问题,后来NASA在阿波罗飞船的导航系统中确实也用到了这个滤波器。最终,飞船正确驶向月球,完成了人类历史上的第一次登月。

本文是国外博主Bzarg在2015年写的一篇图解。虽然是几年前的文章,但是动态定位、自动导航、时间序列模型、卫星导航——卡尔曼滤波的应用范围依然非常广。那么,作为软件工程师和机器学习工程师,你真的了解卡尔曼滤波吗?

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对于之前的MIT课的一些要点概括

Vim

  • Ctrl + d 向下滚动半屏 Ctrl + u 向上滚动半屏
  • w (next word), b (beginning of word), e (end of word)
  • gg 移动到文件头 G(shift + g) 移动到文件尾
  • 0移动到本行第一个字符上 $ 移动到行尾
  • 查找/{regex}, n / N 下一个匹配
  • u 撤销(Undo) Ctrl + r 重做(Redo)
  • 删除d{motion}
  • e.g. dw is delete word, d$ is delete to end of line, d0 is delete to beginning of line
  • 修改c{motion}
    • e.g. cw is change word
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Keyboard remapping

As a programmer, your keyboard is your main input method. As with pretty much anything in your computer, it is configurable (and worth configuring).

The most basic change is to remap keys. This usually involves some software that is listening and, whenever a certain key is pressed, it intercepts that event and replaces it with another event corresponding to a different key. Some examples:

  • Remap Caps Lock to Ctrl or Escape. We (the instructors) highly encourage this setting since Caps Lock has a very convenient location but is rarely used.
  • Remapping PrtSc to Play/Pause music. Most OSes have a play/pause key.
  • Swapping Ctrl and the Meta (Windows or Command) key.
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What do we mean by “metaprogramming”? Well, it was the best collective term we could come up with for the set of things that are more about process than they are about writing code or working more efficiently. In this lecture, we will look at systems for building and testing your code, and for managing dependencies. These may seem like they are of limited importance in your day-to-day as a student, but the moment you interact with a larger code base through an internship or once you enter the “real world”, you will see this everywhere. We should note that “metaprogramming” can also mean “programs that operate on programs”, whereas that is not quite the definition we are using for the purposes of this lecture.

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In this lecture we will go through several ways in which you can improve your workflow when using the shell. We have been working with the shell for a while now, but we have mainly focused on executing different commands. We will now see how to run several processes at the same time while keeping track of them, how to stop or pause a specific process and how to make a process run in the background.

We will also learn about different ways to improve your shell and other tools, by defining aliases and configuring them using dotfiles. Both of these can help you save time, e.g. by using the same configurations in all your machines without having to type long commands. We will look at how to work with remote machines using SSH.

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Have you ever wanted to take data in one format and turn it into a different format? Of course you have! That, in very general terms, is what this lecture is all about. Specifically, massaging data, whether in text or binary format, until you end up with exactly what you wanted.

We’ve already seen some basic data wrangling in past lectures. Pretty much any time you use the | operator, you are performing some kind of data wrangling. Consider a command like journalctl | grep -i intel. It finds all system log entries that mention Intel (case insensitive). You may not think of it as wrangling data, but it is going from one format (your entire system log) to a format that is more useful to you (just the intel log entries). Most data wrangling is about knowing what tools you have at your disposal, and how to combine them.

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Writing English words and writing code are very different activities. When programming, you spend more time switching files, reading, navigating, and editing code compared to writing a long stream. It makes sense that there are different types of programs for writing English words versus code (e.g. Microsoft Word versus Visual Studio Code).

As programmers, we spend most of our time editing code, so it’s worth investing time mastering an editor that fits your needs. Here’s how you learn a new editor:

  • Start with a tutorial (i.e. this lecture, plus resources that we point out)
  • Stick with using the editor for all your text editing needs (even if it slows you down initially)
  • Look things up as you go: if it seems like there should be a better way to do something, there probably is.
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