---

title: "UCSCXenaTools: an R package for Accessing Genomics Data from UCSC Xena platform, from Cancer Multi-omics to Single-cell RNA-seq"

author: "Shixiang Wang \\

        ShanghaiTech University"

date: "`r Sys.Date()`"

output:

  prettydoc::html_pretty:

    toc: true

    theme: cayman

    highlight: github

  pdf_document:

    toc: true

vignette: >

  %\VignetteIndexEntry{Basic usage}

  %\VignetteEngine{knitr::rmarkdown}

  %\usepackage[utf8]{inputenc}

---

```{r setup, include = FALSE}

knitr::opts_chunk$set(

  collapse = TRUE,

  comment = "#>"

)

```

**UCSCXenaTools** is an R package for accessing genomics data from UCSC Xena platform, 

from cancer multi-omics to single-cell RNA-seq. 

Public omics data from UCSC Xena are supported through [**multiple turn-key Xena Hubs**](https://xenabrowser.net/datapages/), which are a collection of UCSC-hosted public databases such as TCGA, ICGC, TARGET, GTEx, CCLE, and others. Databases are normalized so they can be combined, linked, filtered, explored and downloaded.

**Who is the target audience and what are scientific applications of this package?**

* Target Audience: cancer and clinical researchers, bioinformaticians

* Applications: genomic and clinical analyses

## Installation

Install stable release from CRAN with:

```{r, eval=FALSE}

install.packages("UCSCXenaTools")

```

You can also install devel version of **UCSCXenaTools** from github with:

```{r gh-installation, eval = FALSE}

# install.packages("remotes")

remotes::install_github("ropensci/UCSCXenaTools")

```

If you want to build vignette in local, please add two options:

```{r, eval=FALSE}

remotes::install_github("ropensci/UCSCXenaTools", build_vignettes = TRUE, dependencies = TRUE)

```

The minimum versions to run the vignette is `1.2.4`. 

[GitHub Issue](https://github.com/ropensci/UCSCXenaTools/issues) is a place for discussing any problem.

## Data Hub List

All datasets are available at <https://xenabrowser.net/datapages/>.

Currently, **UCSCXenaTools** supports the following data hubs of UCSC Xena.

* UCSC Public Hub: <https://ucscpublic.xenahubs.net/>

* TCGA Hub: <https://tcga.xenahubs.net/>

* GDC Xena Hub: <https://gdc.xenahubs.net/>

* ICGC Xena Hub: <https://icgc.xenahubs.net/>

* Pan-Cancer Atlas Hub: <https://pancanatlas.xenahubs.net/>

* UCSC Toil RNAseq Recompute Compendium Hub: <https://toil.xenahubs.net/>

* PCAWG Xena Hub: <https://pcawg.xenahubs.net/>

* ATAC-seq Hub: <https://atacseq.xenahubs.net/>

* Singel Cell Xena Hub: <https://singlecellnew.xenahubs.net/>

* Kids First Xena Hub: <https://kidsfirst.xenahubs.net/>

* Treehouse Xena Hub: <https://xena.treehouse.gi.ucsc.edu:443/>

Users can update dataset list from the newest version of UCSC Xena by hand with `XenaDataUpdate()` function, followed

by restarting R and `library(UCSCXenaTools)`.

If any url of data hub is changed or a new data hub is online, please remind me by emailing to <w_shixiang@163.com> or [opening an issue on GitHub](https://github.com/ropensci/UCSCXenaTools/issues).

## Usage

Download UCSC Xena datasets and load them into R by **UCSCXenaTools** is a workflow with `generate`, `filter`, `query`, `download` and `prepare` 5 steps, which are implemented as `XenaGenerate`, `XenaFilter`, `XenaQuery`, `XenaDownload` and `XenaPrepare` functions, respectively. They are very clear and easy to use and combine with other packages like `dplyr`.

To show the basic usage of **UCSCXenaTools**, we will download clinical data of LUNG, LUAD, LUSC from TCGA (hg19 version) data hub.

### XenaData data.frame

**UCSCXenaTools** uses a `data.frame` object (built in package) `XenaData` to generate an instance of `XenaHub` class, which records information of all datasets of UCSC Xena Data Hubs.

You can load `XenaData` after loading `UCSCXenaTools` into R.

```{r}

library(UCSCXenaTools)

data(XenaData)

head(XenaData)

```

### Workflow

Select datasets.

```{r}

# The options in XenaFilter function support Regular Expression

XenaGenerate(subset = XenaHostNames=="tcgaHub") %>% 

  XenaFilter(filterDatasets = "clinical") %>% 

  XenaFilter(filterDatasets = "LUAD|LUSC|LUNG") -> df_todo

df_todo

```

Sometimes we only know some keywords, `XenaScan()` can be used to scan all rows to detect if 

the keywords exist in `XenaData`.

```{r}

x1 = XenaScan(pattern = 'Blood')

x2 = XenaScan(pattern = 'LUNG', ignore.case = FALSE)

x1 %>%

    XenaGenerate()

x2 %>%

    XenaGenerate()

```

Query and download.

```{r}

XenaQuery(df_todo) %>%

  XenaDownload() -> xe_download

```

Prepare data into R for analysis.

```{r}

cli = XenaPrepare(xe_download)

class(cli)

names(cli)

```

### Browse datasets

Create two XenaHub objects:

* `to_browse` - a XenaHub object containing a cohort and a dataset.

* `to_browse2` - a XenaHub object containing 2 cohorts and 2 datasets.

```{r}

XenaGenerate(subset = XenaHostNames=="tcgaHub") %>%

    XenaFilter(filterDatasets = "clinical") %>%

    XenaFilter(filterDatasets = "LUAD") -> to_browse

to_browse

XenaGenerate(subset = XenaHostNames=="tcgaHub") %>%

    XenaFilter(filterDatasets = "clinical") %>%

    XenaFilter(filterDatasets = "LUAD|LUSC") -> to_browse2

to_browse2

```

`XenaBrowse()` function can be used to browse dataset/cohort links using your default web browser.

At default, this function limits one dataset/cohort for preventing user to open too many links at once. 

```{r,eval=FALSE}

# This will open you web browser

XenaBrowse(to_browse)

XenaBrowse(to_browse, type = "cohort")

```

```{r, error=TRUE}

# This will throw error

XenaBrowse(to_browse2)

XenaBrowse(to_browse2, type = "cohort")

```

When you make sure you want to open multiple links, you can set `multiple` option to `TRUE`.

```{r, eval=FALSE}

XenaBrowse(to_browse2, multiple = TRUE)

XenaBrowse(to_browse2, type = "cohort", multiple = TRUE)

```

## More usages

The core functionality has been described above. 

I write more usages about this package in my website but not here

because sometimes package check will fail due to internet problem.

- [Introduction and basic usage of UCSCXenaTools](https://shixiangwang.github.io/home/en/tools/ucscxenatools-intro/) - [PDF](https://shixiangwang.github.io/home/en/tools/ucscxenatools-intro.pdf)

- [APIs of UCSCXenaTools](https://shixiangwang.github.io/home/en/tools/ucscxenatools-api/) - [PDF](https://shixiangwang.github.io/home/en/tools/ucscxenatools-api.pdf)

Read [Obtain RNAseq Values for a Specific Gene in Xena Database](https://shixiangwang.github.io/home/en/tools/ucscxenatools-single-gene/) to see how to get values for single gene. A use case for survival analysis based on single gene expression has been published on rOpenSci, please read

[UCSCXenaTools: Retrieve Gene Expression and Clinical Information from UCSC Xena for Survival Analysis](https://ropensci.org/technotes/2019/09/06/ucscxenatools-surv/).

## QA

### How to resume file from breakpoint

Thanks to the UCSC Xena team, the new feature 'resume from breakpoint' is added and 

can be done by **XenaDownload()** with the `method` and `extra` flags specified.

Of note, the corresponding `wget` or `curl` command must be installed by your OS

and can be found by R.

The folliwng code gives a test example, the data can be viewed on [web page](https://xenabrowser.net/datapages/?dataset=TcgaTargetGtex_expected_count&host=https%3A%2F%2Ftoil.xenahubs.net&removeHub=https%3A%2F%2Fxena.treehouse.gi.ucsc.edu%3A443).

```r

library(UCSCXenaTools)

xe = XenaGenerate(subset = XenaDatasets == "TcgaTargetGtex_expected_count")

xe

xq = XenaQuery(xe)

# You cannot resume from breakpoint in default mode

XenaDownload(xq, destdir = "~/test/", force = TRUE)

# You can do it with 'curl' command

XenaDownload(xq, destdir = "~/test/", method = "curl", extra = "-C -", force = TRUE)

# You can do it with 'wget' command

XenaDownload(xq, destdir = "~/test/", method = "wget", extra = "-c", force = TRUE)

```

## Citation

Cite me by the following paper.

```

Wang et al., (2019). The UCSCXenaTools R package: a toolkit for accessing genomics data

  from UCSC Xena platform, from cancer multi-omics to single-cell RNA-seq. 

  Journal of Open Source Software, 4(40), 1627, https://doi.org/10.21105/joss.01627

# For BibTex

@article{Wang2019UCSCXenaTools,

    journal = {Journal of Open Source Software},

    doi = {10.21105/joss.01627},

    issn = {2475-9066},

    number = {40},

    publisher = {The Open Journal},

    title = {The UCSCXenaTools R package: a toolkit for accessing genomics data from UCSC Xena platform, from cancer multi-omics to single-cell RNA-seq},

    url = {http://dx.doi.org/10.21105/joss.01627},

    volume = {4},

    author = {Wang, Shixiang and Liu, Xuesong},

    pages = {1627},

    date = {2019-08-05},

    year = {2019},

    month = {8},

    day = {5},

}

```

Cite UCSC Xena by the following paper. 

```

Goldman, Mary, et al. "The UCSC Xena Platform for cancer genomics data 

    visualization and interpretation." BioRxiv (2019): 326470.

```

## Acknowledgments

This package is based on [XenaR](https://github.com/mtmorgan/XenaR), thanks [Martin Morgan](https://github.com/mtmorgan) for his work.