```{r setup，echo = false}库（searchbiociondumon）stopifnot（Biocinstaller :: biocversion（）==“3.0”）``````:: Markdown（）```＃组织函数，文件和包中的代码Martin Morgan
2014年10月29日##编程_R_是一种编程语言 - 您自己的功能```{r fun} fun < - function（n）{x < - rnorm（n）y < - x + rnorm（n，sd =。5）LM（Y〜x）}``` - 查看_rstudio_函数向导！- 迭代```{r reateration，eval = false} ##'副作用'（I在1:10）消息（i）##后续计算的结果sapply（1:10，function（i）{sum（rnorm（1000））}）``` - 其他迭代范例：`lapply（）`，`apply（）`，`mapply（）/ map（）`。- 条件执行```{R条件，eval = false} Sapply（1:10，功能（i））{if（sum（rnorm（1000））> 0）{“hi！”}否则{“低！”从脚本到包脚本的``##包含数据和转换的组合。通常，转换通常是特殊的，并且严重依赖各种包提供的功能。有时，脚本包含一个有用的代码块，可以在不同的地方重用。我们在本课程中遇到的例子可能包括DNA序列的GC含量（或者已经有一个功能？查看`R Biocpkg（“BioStrings”）“！）并从一种类型创建一个简单的”地图“向另一个注释。创建一个包很容易和有益。 - Only need to think carefully about how to implement the function once. - Code in the package is reused -- if you correct an error, then all your scripts automatically benefit. - Share with your lab mates / colleagues for consistent results, and with the wider community for fame and glory. What is an _R_ package? - Simple directory structure of required files. Minimal: MyPackage |-- DESCRIPTION (title, author, version, etc.) |-- NAMESPACE (imports / exports) |-- R (R function definitions) |-- gc.R |-- annoHelper.R |-- man (help pages) |-- MyPackage.Rd |-- gc.Rd |-- annoHelper.Rd Check out the _Rstudio_ package wizard! ## Lab ### GC-content Write a function that takes a `DNAStringSet` and returns the GC content. Modify the function using a conditional statement to work whether provided a `DNAString` or a `DNAStringSet`. Test the function. Save the function in a file on your AMI. ### Annotation-helper Write a function that takes as its argument Ensembl gene identifiers (like the `rownames()` of the _SummarizedExperiment_ object in the RNASeq vignette yesterday) and uses the `select()` method and annotation package `r Biocannopkg("org.Hs.eg.db")` to return a named character vector, where the names of the vector are the Ensembl identifiers and the values are the corresponding gene SYMBOLs. Adopt some simple-to-implement policy for handling Ensembl identifiers that map to more than one gene symbol. Save this function to another file ### A package Use the _RStudio_ wizard to create a package from the files containing your GC-content and annotation-helper functions.