你好，我是悦创。
今天我们来讲讲 Rust 语言设计的出发点——所有权，它也是 Rust 的精髓所在。
在第一节课中，我们了解了 Rust 语言里的值有两大类：一类是固定内存长度（简称固定尺寸）的值，比如 i32、u32、由固定尺寸的类型组成的结构体等；另一类是不固定内存长度（简称非固定尺寸）的值，比如字符串 String。这两种值的本质特征完全不一样。而怎么处理这两种值的差异，往往是语言设计的差异性所在。
就拿数字类型来说，C、C++、Java 这些语言就明确定义了数字类型会占用内存中的几个字节，比如 8 位，也就是一个字节，16 位，也就是两个字节。而 JavaScript 这种语言，就完全屏蔽了底层的细节，统一用一个 Number 表示数字。Python 则给出了 int 整数、float 浮点、complex 复数三种数字类型。
你好，我是悦创。今天是我们的 Rust 入门与实战第一讲。
无论对人，还是对事儿，第一印象都很重要，Rust 也不例外。今天我们就来看一看 Rust 给人的第一印象是什么吧。其实 Rust 宣称的安全、高性能、无畏并发这些特点，初次接触的时候都是感受不到的。第一次能直观感受到的实际是下面这些东西。
你好，我是悦创。欢迎加入《Rust 语言从入门到实战》，开启一段全新的学习旅程。
2018 年我开始接触 Rust，到现在已经 6 年多了，从拥护者到布道者，一直在学习积累。
我以前是一个 C 极大主义者「在大学中时」，觉得用 C 语言就能完成我想做的任何事情。但后来 C 程序中的各种缓冲区溢出、段错误等问题一直困扰着我，不管我采用何种最佳实践集合，那些问题总是根除不了。
这也是我学习 Rust 的重要契机。那时我就有种直觉——它一定会成为未来的一股潮流。
在许多情况下，你需要根据条件做出决定。
为此，可以使用 if 语句。
例如：
x <- 24
if(x > 10){
print( "x is greater than 10")
}
你好，我是悦创。
R 语言是应用最广泛的统计编程语言。
而且 R 语言它是数据科学家和分析师的首选。
在本课程中，我们将学习R语言的基础知识，了解如何创建存储和操作数据的程序、以及如何使用各种数据集执行数据分析任务，以及如何使用图形和图表可视化结果。
本课程学习的技能可应用于任何与数据相关的领域，包括金融、数据科学、机器学习等。
Assignment 1 is designed to test your understanding of the skills practiced in weeks 1 through 4:
What kind of data structure is user_data in the following declaration?
user_data = ("TJ", 24, "artLover123")
Netiquette is essentially rules and norms for interacting with others on the Internet.
We’re here to help with nine simple guidelines for how to be on your best behavior in an online classroom.
In order to participate in this course within Canvas, you should make sure that your technologies meet the minimal basic computer specificationsLinks to an external site..
(0 points) Please type your code and answers into Jupyter notebook. All visualizations should be prop-erly labelled. Submit the notebook as a pdf.
(3.5 points) Use the bwght dataset from the Wooldridge python module to answer the following question. You can find the documentation for the data online here. Import this data into your notebook.
(a) (1.5 Points) How many women are in the sample? What proportion of women with a family income higher than $50,000 are smokers? What proportion of women with a family income less than $20,000 are smokers?
(b) (1 Points) Generate a table of summary statistics for the dataframe. What is the average number of cigarettes smoked in a day? Is the mean a good measure of the typical women’s smoking habits? If no, explain why and if there is a better measure.
(c) (1 Points) Find the mode of fatheduc in the sample. Why are only 1,192 observations used to compute this statistic?
(5.5 points) Use the bwght dataset from the Wooldridge python module to answer the following question.
(a) (1 point) Generate two different histograms of bwght using Sturge’s and FD binning methods. Explain the strengths and weaknesses of each method when applied to bwght.
(b) (1 point) Create a histogram of bwght using either sturges or fd to choose the number of bins. Overlay a density curve.
(c) (2 points) Using a q-q plot, do you believe bwght is approximately normally distributed? Why are why not? What about family income?
(d) (1.5 points) Create a boxplot conditioning on whether or not the mother was a smoker. Do you observe any differences? If so, what are they?
(6 points) Use the bwght dataset from the Wooldridge python module to answer the following question.
(a) (2 points) Estimate the parameters for the following simple regression:
report the intercept and slope. What do these tell you about the association between cigarette use and birth weight?
(b) (2 points) What is the predicted value of birthweight when packs = 0? When packs = 2? What is the interpretation of the intercept?
(c) (1 point) Verify the residuals of this regression sum (approximately) to zero.
(d) (1 point) Using a scatter plot, show the observed values against the values predicted by a regression.
Create a list of your favorite 4 movies. Print out the 0th element in the list. Now set the 0th element to be “Star Wars” and try printing it out again.
创建你最喜欢的4部电影的列表。打印列表中的第0个元素。现在将第0个元素设置为“星球大战”，然后再试着打印它。
# 创建一个包含4部电影的列表
favorite_movies = ["Movie1", "Movie2", "Movie3", "Movie4"]
# 打印列表中的第0个元素
print(favorite_movies[0])
# 将第0个元素设置为“星球大战”
favorite_movies[0] = "星球大战"
# 再次打印列表中的第0个元素
print(favorite_movies[0])
使用命令行运行 Jupyter Notebook 的具体流程如下：
jupyter notebook
In the following code:「D」
size = 20
x = 100
y = 200
ball = Circle(size)
circle.set_position(x, y)
Write a function that takes one parameter - a float which represents a temperature in Celsius - and returns a float which represents that temperature in Fahrenheit.
Then, write a function that does the opposite conversion.
Here are the formulas for temperature conversion: