## 统计代写|R语言代写R language代考|STIN300

2022年12月23日

R是一种用于统计计算和图形的编程语言，由R核心团队和R统计计算基金会支持。R由统计学家Ross Ihaka和Robert Gentleman创建，在数据挖掘者和统计学家中被用于数据分析和开发统计软件。用户已经创建了软件包来增强R语言的功能。

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• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础
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## 统计代写|R语言代写R language代考|The ‘mode’ and ‘class’ of objects

Variables have a mode that depends on what is stored in them. But different from other languages, assignment to a variable of a different mode is allowed and in most cases its mode changes together with its contents. However, there is a restriction that all elements in a vector, array or matrix, must be of the same mode. While this is not required for lists, which can be heterogenous. In practice this means that we can assign an object, such as a vector, with a different mode to a name already in use, but we cannot use indexing to assign an object of a different mode to individual members of a vector, matrix or array. Functions with names starting with is. are tests returning a logical value, TRUE, FALSE or NA. Function mode() returns the mode of an object, as a character string and typeof() returns $R^{\prime}$ s internal type or storage mode.

While mode is a fundamental property, and limited to those modes defined as part of the R language, the concept of class, is different in that new classes can be defined in user code. In particular, different R objects of a given mode, such as numeric, can belong to different classes. The use of classes for dispatching functions is discussed in section $5.4$ on page 172 , in relation to object-oriented programming in R. Method class() is used to query the class of an object, and method inherits() is used to test if an object belongs to a specific class or not (including “parent” classes, to be later described).

## 统计代写|R语言代写R language代考|Vector manipulation

If you have read earlier sections of this chapter, you already know how to create a vector. R’s vectors are equivalent to what would be written in mathematical notation as $x_{1 \ldots n}=a_1, a_2, \ldots, a_i, \ldots, a_n$, they are not the equivalent to the vectors, common in Physics, which are symbolized with an arrow as an “accent,” such as $\overrightarrow{\mathbf{F}}$.
In this section we are going to see how to extract or retrieve, replace, and move elements such as $a_2$ from a vector. Elements are extracted using an index enclosed in single square brackets. The index indicates the position in the vector, starting from one, following the usual mathematical tradition. What in maths would be $a_i$ for a vector $a_{1 \ldots n}$, in $\mathrm{R}$ is represented as a [i] and the whole vector as earlier seen as a.

It is possible to extract a subset of the elements of a vector in a single operation, using a vector of indexes. The positions of the extracted elements in the result (“returned value”) are determined by the ordering of the members of the vector of indexes-easier to demonstrate than to explain.

Negative indexes have a special meaning; they indicate the positions at which values should be excluded. Be aware that it is illegal to mix positive and negative values in the same indexing operation.

# R语言代写

## 有限元方法代写

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## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。