R 简明教程

R - Packages

R 包是 R 函数、已编译代码和样本数据的集合。它们被存储在 R 环境中名为 "library" 的目录下。默认情况下，R 在安装过程中安装了一组包。当它们被用于某些特定目的时，后期还会添加更多的包。当我们启动 R 控制台时，默认情况下只有默认包可用。必须显式加载其他已安装的包，才能让将要使用它们的 R 程序访问它们。

R packages are a collection of R functions, complied code and sample data. They are stored under a directory called "library" in the R environment. By default, R installs a set of packages during installation. More packages are added later, when they are needed for some specific purpose. When we start the R console, only the default packages are available by default. Other packages which are already installed have to be loaded explicitly to be used by the R program that is going to use them.

R 语言中所有可用的包均在 R Packages. 列出。

All the packages available in R language are listed at R Packages.

下方是用于检查、验证和使用 R 包的命令列表。

Below is a list of commands to be used to check, verify and use the R packages.

Check Available R Packages

获取包含 R 包的库位置

Get library locations containing R packages

.libPaths()

当我们执行以上代码时，它会生成以下结果。结果可能根据电脑的本地设置有所不同。

When we execute the above code, it produces the following result. It may vary depending on the local settings of your pc.

[2] "C:/Program Files/R/R-3.2.2/library"

Get the list of all the packages installed

library()

当我们执行以上代码时，它会生成以下结果。结果可能根据电脑的本地设置有所不同。

When we execute the above code, it produces the following result. It may vary depending on the local settings of your pc.

Packages in library ‘C:/Program Files/R/R-3.2.2/library’:

base                    The R Base Package
boot                    Bootstrap Functions (Originally by Angelo Canty
                        for S)
class                   Functions for Classification
cluster                 "Finding Groups in Data": Cluster Analysis
                        Extended Rousseeuw et al.
codetools               Code Analysis Tools for R
compiler                The R Compiler Package
datasets                The R Datasets Package
foreign                 Read Data Stored by 'Minitab', 'S', 'SAS',
                        'SPSS', 'Stata', 'Systat', 'Weka', 'dBase', ...
graphics                The R Graphics Package
grDevices               The R Graphics Devices and Support for Colours
                        and Fonts
grid                    The Grid Graphics Package
KernSmooth              Functions for Kernel Smoothing Supporting Wand
                        & Jones (1995)
lattice                 Trellis Graphics for R
MASS                    Support Functions and Datasets for Venables and
                        Ripley's MASS
Matrix                  Sparse and Dense Matrix Classes and Methods
methods                 Formal Methods and Classes
mgcv                    Mixed GAM Computation Vehicle with GCV/AIC/REML
                        Smoothness Estimation
nlme                    Linear and Nonlinear Mixed Effects Models
nnet                    Feed-Forward Neural Networks and Multinomial
                        Log-Linear Models
parallel                Support for Parallel computation in R
rpart                   Recursive Partitioning and Regression Trees
spatial                 Functions for Kriging and Point Pattern
                        Analysis
splines                 Regression Spline Functions and Classes
stats                   The R Stats Package
stats4                  Statistical Functions using S4 Classes
survival                Survival Analysis
tcltk                   Tcl/Tk Interface
tools                   Tools for Package Development
utils                   The R Utils Package

获取 R 环境中当前加载的所有包

Get all packages currently loaded in the R environment

search()

当我们执行以上代码时，它会生成以下结果。结果可能根据电脑的本地设置有所不同。

When we execute the above code, it produces the following result. It may vary depending on the local settings of your pc.

[1] ".GlobalEnv"        "package:stats"     "package:graphics"
[4] "package:grDevices" "package:utils"     "package:datasets"
[7] "package:methods"   "Autoloads"         "package:base"

Install a New Package

有两种添加新 R 包的方法。一种是直接从 CRAN 目录安装，另一种是将包下载至本地系统并手动安装。

There are two ways to add new R packages. One is installing directly from the CRAN directory and another is downloading the package to your local system and installing it manually.

Install directly from CRAN

以下命令直接从 CRAN 网页获取包，并将包安装至 R 环境。系统可能会提示你选择最近的镜像。选择一个适合你所在位置的镜像。

The following command gets the packages directly from CRAN webpage and installs the package in the R environment. You may be prompted to choose a nearest mirror. Choose the one appropriate to your location.

 install.packages("Package Name")

# Install the package named "XML".
 install.packages("XML")

Install package manually

前往链接 R Packages 下载所需的包。将包另存为 .zip 文件至本地系统中的适当位置。

Go to the link R Packages to download the package needed. Save the package as a .zip file in a suitable location in the local system.

现在，你可以运行以下命令以在 R 环境中安装此包。

Now you can run the following command to install this package in the R environment.

install.packages(file_name_with_path, repos = NULL, type = "source")

# Install the package named "XML"
install.packages("E:/XML_3.98-1.3.zip", repos = NULL, type = "source")

Load Package to Library

在代码中使用包之前，必须先将其加载至当前 R 环境。你还可以加载之前已安装但当前环境中不可用的包。

Before a package can be used in the code, it must be loaded to the current R environment. You also need to load a package that is already installed previously but not available in the current environment.

使用以下命令加载包 −

A package is loaded using the following command −

library("package Name", lib.loc = "path to library")

# Load the package named "XML"
install.packages("E:/XML_3.98-1.3.zip", repos = NULL, type = "source")