---
title: "trackViewer Vignette: plot interaction data"
author: "Jianhong Ou, Lihua Julie Zhu"
date: "`r BiocStyle::doc_date()`"
package: "`r BiocStyle::pkg_ver('trackViewer')`"
abstract: >
  Visualize chromatin interactions along with annotation as track layers.
  The interactions can be compared by back to back heatmaps. 
  The interactions can be plot as heatmap and links.
vignette: >
  %\VignetteIndexEntry{trackViewer Vignette: plot interaction data}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
output:
  html_document:
    theme: simplex
    toc: true
    toc_float: true
    toc_depth: 4
    fig_caption: true
---

```{r, echo=FALSE, results="hide", warning=FALSE}
suppressPackageStartupMessages({
  library(trackViewer)
  library(TxDb.Hsapiens.UCSC.hg19.knownGene)
  library(InteractionSet)
})
knitr::opts_chunk$set(warning=FALSE, message=FALSE)
```

# Introduction

The chromatin interactions is involved in precise quantitative and spatiotemporal
control of gene expression. The development of high-throughput experimental 
techniques, such as HiC-seq, HiCAR-seq, and InTAC-seq, for analyzing both the 
higher-order structure of chromatin and the interactions between protein and
their nearby and remote regulatory elements has been developed to reveal how
gene expression is controlled in genome-wide.

The interaction data will be saved in the format of paired genome coordinates
with the interaction score. The popular format are `.validPairs`, `.hic`, and
`.cool`. The `trackViewer` package can be used to handle those data to plot
the heatmap or the interaction links.

# Plot chromatin interactions data

Plot chromatin interactions tracks as heatmap.

```{r plotback2back}
library(trackViewer)
library(InteractionSet)
gi <- readRDS(system.file("extdata", "nij.chr6.51120000.53200000.gi.rds", package="trackViewer"))
head(gi)
## hicexplorer:hicConvertFormat tool can be used to convert other formats into GInteractions
## eg: hicConvertFormat -m mESC_rep.hic --inputFormat hic --outputFormat cool -o mESC_rep.mcool
##     hicConvertFormat -m mESC_rep.mcool::resolutions/10000 --inputFormat cool --outputFormat ginteractions -o mESC_rep.ginteractions --resolutions 10000
## please note that metadata:score is used for plot.
gi$border_color <- NA ## highlight some regions
gi$border_color[sample(seq_along(gi), 20)] <- sample(1:7, 20, replace=TRUE)
## The TADs will be drawn as lines at points start(first), center point, end(second).
tads <- GInteractions(
  GRanges("chr6", 
          IRanges(c(51130001, 51130001, 51450001, 52210001), width = 20000)),
  GRanges("chr6", 
          IRanges(c(51530001, 52170001, 52210001, 53210001), width = 20000)))
range <- GRanges("chr6", IRanges(51120000, 53200000))
heatmap <- gi2track(gi)
ctcf <- readRDS(system.file("extdata", "ctcf.sample.rds", package="trackViewer"))
viewTracks(trackList(ctcf, heatmap, heightDist = c(1, 3)), 
           gr=range, autoOptimizeStyle = TRUE)
## add TAD information
addInteractionAnnotation(tads, "heatmap", grid.lines, gp=gpar(col="#E69F00", lwd=3, lty=3))
## add highlight interested regions
gi_sub <- gi[order(gi$score, decreasing = TRUE)]
gi_sub <- head(gi_sub[distance(first(gi_sub), second(gi_sub))>200000], n=5)
start(regions(gi_sub)) <- start(regions(gi_sub))-40000
end(regions(gi_sub)) <- end(regions(gi_sub))+40000
addInteractionAnnotation(gi_sub, "heatmap", grid.polygon, gp=gpar(col="red", lwd=2, lty=2, fill=NA))
## add interesting anchor at giving coordinate.
addInteractionAnnotation(52900000, "heatmap", gp=gpar(col="blue", lwd=3))
addInteractionAnnotation(-52900000, "heatmap", gp=gpar(col="cyan", lwd=3, lty=4))
## view the interaction data back to back.
## Please make sure the data are normalized.
gi2 <- gi
set.seed(123)
gi2$score <- gi$score + rnorm(length(gi), sd = sd(gi$score))
back2back <- gi2track(gi, gi2)
## change the color
setTrackStyleParam(back2back, "breaks", 
                   c(seq(from=0, to=50, by=10), 200))
setTrackStyleParam(back2back, "color",
                   c("lightblue", "yellow", "red"))
## chang the lim of y-axis (by default, [0, 1])
setTrackStyleParam(back2back, "ylim", c(0, .5))
viewTracks(trackList(ctcf, back2back, heightDist=c(1, 5)),
           gr=range, autoOptimizeStyle = TRUE)
addInteractionAnnotation(tads, "back2back", grid.lines,
                         gp=gpar(col="cyan", lwd=3, lty=2))
addInteractionAnnotation(-52208000, "back2back", gp=gpar(col="blue", lwd=3),
                         panel="top")
addInteractionAnnotation(51508000, "back2back", gp=gpar(col="gray", lwd=3, lty=2),
                         panel="bottom")
```

Plot chromatin interactions track as links.

```{r plotLinks, fig.width=6, fig.height=3}
setTrackStyleParam(heatmap, "tracktype", "link")
setTrackStyleParam(heatmap, "breaks", 
                   c(seq(from=0, to=50, by=10), 200))
setTrackStyleParam(heatmap, "color",
                   c("lightblue", "yellow", "red"))
## filter the links to simulate the real data
keep <- distance(heatmap$dat, heatmap$dat2) > 5e5 & heatmap$dat$score>20
heatmap$dat <- heatmap$dat[keep]
heatmap$dat2 <- heatmap$dat2[keep]
viewTracks(trackList(heatmap), gr=range, autoOptimizeStyle = TRUE)
```


To import interactions data from ".hic" (reference to 
the script of [hic-straw](https://github.com/aidenlab/straw) and the
[documentation](https://www.cell.com/cms/10.1016/j.cels.2016.07.002/attachment/ce39448c-9a11-4b4e-a03f-45882b7b1d9d/mmc2.xlsx)). 
The function `importGInteractions` (trackViewer version>=1.27.6) can be used to
import data from `.hic` format file.

```{r inportHic}
hic <- system.file("extdata", "test_chr22.hic", package = "trackViewer",
                    mustWork=TRUE)
if(.Platform$OS.type!="windows"){
importGInteractions(file=hic, format="hic",
                    ranges=GRanges("22", IRanges(50000000, 100000000)),
                    out = "GInteractions")
}
```

Another widely used genomic interaction data format is `.cool` files and the
[cooler index](ftp://cooler.csail.mit.edu/coolers) contains analyzed HiC data
for hg19 and mm9 from many different sources. Those files can be used as data
resources for visualizations and annotations 
(see [ChIPpeakAnno::findEnhancers](https://rdrr.io/bioc/ChIPpeakAnno/man/findEnhancers.html)).
The `importGInteractions` function can also be used to import data from `.cool` format (trackViewer version>=1.27.6).
```{r importCool, eval=FALSE}
cool <- system.file("extdata", "test.mcool", package = "trackViewer",
                     mustWork=TRUE)
importGInteractions(file=cool, format="cool",
                    resolution = 2,
                    ranges=GRanges("chr1", IRanges(10, 28)),
                    out = "GInteractions")
```


Different from most of the available tools, plotGInteractions try to plot the data with the 2D structure. The nodes indicate the region with interactions and
the edges indicates the interactions. The size of the nodes are relative to the width of the region.
The features could be the enhancers, promoters or genes. The enhancer and promoter are shown as
points with symbol 11 and 13.

```{r plotGInteractions}
library(TxDb.Hsapiens.UCSC.hg19.knownGene)
library(InteractionSet)
gi <- readRDS(system.file("extdata", "gi.rds", package="trackViewer"))
range <- GRanges("chr2", IRanges(234500000, 235000000))
feature.gr <- suppressMessages(genes(TxDb.Hsapiens.UCSC.hg19.knownGene))
feature.gr <- subsetByOverlaps(feature.gr, regions(gi))
feature.gr$col <- sample(1:7, length(feature.gr), replace=TRUE)
feature.gr$type <- sample(c("promoter", "enhancer", "gene"), 
                          length(feature.gr), replace=TRUE, 
                          prob=c(0.1, 0.2, 0.7))
plotGInteractions(gi, range, feature.gr)
```

# Session Info
```{r sessionInfo, results='asis'}
sessionInfo()
```

