ggcoverage - Visualize and annotate genome coverage with ggplot2

Introduction

The goal of ggcoverage is simplify the process of visualizing genome coverage. It contains three main parts:

• Load the data: ggcoverage can load BAM, BigWig (.bw), BedGraph files from various NGS data, including WGS, RNA-seq, ChIP-seq, ATAC-seq, et al.
• Create genome coverage plot
• Add annotations: ggcoverage supports six different annotations:
  • base and amino acid annotation: Visualize genome coverage at single-nucleotide level with bases and amino acids.
  • GC annotation: Visualize genome coverage with GC content
  • gene annotation: Visualize genome coverage across whole gene
  • transcription annotation: Visualize genome coverage across different transcripts
  • ideogram annotation: Visualize the region showing on whole chromosome
  • peak annotation: Visualize genome coverage and peak identified

ggcoverage utilizes ggplot2 plotting system, so its usage is ggplot2-style!

Installation

ggcoverage is an R package distributed as part of the CRAN. To install the package, start R and enter:

# install via CRAN
install.package("ggcoverage")

# install via Github
# install.package("remotes")   #In case you have not installed it.
remotes::install_github("showteeth/ggcoverage")

In general, it is recommended to install from Github repository (update more timely).

Once ggcoverage is installed, it can be loaded by the following command.

library("rtracklayer")
library("ggcoverage")

RNA-seq data

Load the data

The RNA-seq data used here are from Transcription profiling by high throughput sequencing of HNRNPC knockdown and control HeLa cells, we select four sample to use as example: ERR127307_chr14, ERR127306_chr14, ERR127303_chr14, ERR127302_chr14, and all bam files are converted to bigwig file with deeptools.

Load metadata:

# load metadata
meta.file <- system.file("extdata", "RNA-seq", "meta_info.csv", package = "ggcoverage")
sample.meta = read.csv(meta.file)
sample.meta
#>        SampleName    Type Group
#> 1 ERR127302_chr14 KO_rep1    KO
#> 2 ERR127303_chr14 KO_rep2    KO
#> 3 ERR127306_chr14 WT_rep1    WT
#> 4 ERR127307_chr14 WT_rep2    WT

Load track files:

# track folder
track.folder = system.file("extdata", "RNA-seq", package = "ggcoverage")
# load bigwig file
track.df = LoadTrackFile(track.folder = track.folder, format = "bw",
                         meta.info = sample.meta)
# check data
head(track.df)
#>   seqnames    start      end score    Type Group
#> 1    chr14 21572751 21630650     0 KO_rep1    KO
#> 2    chr14 21630651 21630700     1 KO_rep1    KO
#> 3    chr14 21630701 21630800     4 KO_rep1    KO
#> 4    chr14 21630801 21657350     0 KO_rep1    KO
#> 5    chr14 21657351 21657450     1 KO_rep1    KO
#> 6    chr14 21657451 21663550     0 KO_rep1    KO

Prepare mark region:

# create mark region
mark.region=data.frame(start=c(21678900,21732001,21737590),
                       end=c(21679900,21732400,21737650),
                       label=c("M1", "M2", "M3"))
# check data
mark.region
#>      start      end label
#> 1 21678900 21679900    M1
#> 2 21732001 21732400    M2
#> 3 21737590 21737650    M3

Load GTF file:

gtf.file = system.file("extdata", "used_hg19.gtf", package = "ggcoverage")
gtf.gr = rtracklayer::import.gff(con = gtf.file, format = 'gtf')

Basic coverage

basic.coverage = ggcoverage(data = track.df, color = "auto", 
                            mark.region = mark.region, range.position = "out")
basic.coverage

You can also change Y axis style:

basic.coverage = ggcoverage(data = track.df, color = "auto", 
                            mark.region = mark.region, range.position = "in")
basic.coverage

Add gene annotation

basic.coverage + 
  geom_gene(gtf.gr=gtf.gr)

Add transcript annotation

basic.coverage + 
  geom_transcript(gtf.gr=gtf.gr,label.vjust = 1.5)

Add ideogram

basic.coverage +
  geom_gene(gtf.gr=gtf.gr) +
  geom_ideogram(genome = "hg19",plot.space = 0)
#> Loading ideogram...
#> Loading ranges...
#> Scale for 'x' is already present. Adding another scale for 'x', which will
#> replace the existing scale.

basic.coverage +
  geom_transcript(gtf.gr=gtf.gr,label.vjust = 1.5) +
  geom_ideogram(genome = "hg19",plot.space = 0)
#> Loading ideogram...
#> Loading ranges...
#> Scale for 'x' is already present. Adding another scale for 'x', which will
#> replace the existing scale.

DNA-seq data

CNV

Load the data

The DNA-seq data used here are from Copy number work flow, we select tumor sample, and get bin counts with cn.mops::getReadCountsFromBAM with WL 1000.

# track file
track.file = system.file("extdata", "DNA-seq", "CNV_example.txt", package = "ggcoverage")
track.df = read.table(track.file, header = TRUE)
# check data
head(track.df)
#>   seqnames    start      end score  Type Group
#> 1     chr4 61743001 61744000    17 tumor tumor
#> 2     chr4 61744001 61745000    14 tumor tumor
#> 3     chr4 61745001 61746000    13 tumor tumor
#> 4     chr4 61746001 61747000    16 tumor tumor
#> 5     chr4 61747001 61748000    25 tumor tumor
#> 6     chr4 61748001 61749000    24 tumor tumor

Basic coverage

basic.coverage = ggcoverage(data = track.df,color = NULL, mark.region = NULL,
                            region = 'chr4:61750000-62,700,000', range.position = "out")
basic.coverage

Add GC annotations

Add GC, ideogram and gene annotaions.

# load genome data
library("BSgenome.Hsapiens.UCSC.hg19")
#> Loading required package: BSgenome
#> Loading required package: Biostrings
#> Loading required package: XVector
#> 
#> Attaching package: 'Biostrings'
#> The following object is masked from 'package:base':
#> 
#>     strsplit
# create plot
basic.coverage +
  geom_gc(bs.fa.seq=BSgenome.Hsapiens.UCSC.hg19) +
  geom_gene(gtf.gr=gtf.gr) +
  geom_ideogram(genome = "hg19")
#> Loading ideogram...
#> Loading ranges...
#> Scale for 'x' is already present. Adding another scale for 'x', which will
#> replace the existing scale.

Single-nucleotide level

Load the data

# prepare sample metadata
sample.meta <- data.frame(
  SampleName = c("tumorA.chr4.selected"),
  Type = c("tumorA"),
  Group = c("tumorA")
)
# load bam file
bam.file = system.file("extdata", "DNA-seq", "tumorA.chr4.selected.bam", package = "ggcoverage")
track.df <- LoadTrackFile(
  track.file = bam.file,
  meta.info = sample.meta,
  single.nuc=TRUE, single.nuc.region="chr4:62474235-62474295"
)
head(track.df)
#>   seqnames    start      end score   Type  Group
#> 1     chr4 62474235 62474236     5 tumorA tumorA
#> 2     chr4 62474236 62474237     5 tumorA tumorA
#> 3     chr4 62474237 62474238     5 tumorA tumorA
#> 4     chr4 62474238 62474239     6 tumorA tumorA
#> 5     chr4 62474239 62474240     6 tumorA tumorA
#> 6     chr4 62474240 62474241     6 tumorA tumorA

Default color scheme

For base and amino acid annotation, we have following default color schemes, you can change with nuc.color and aa.color parameters.

Default color scheme for base annotation is Clustal-style, more popular color schemes is available here.

# color scheme
nuc.color = c("A" = "#ff2b08", "C" = "#009aff", "G" = "#ffb507", "T" = "#00bc0d")
# create plot
graphics::par(mar = c(1, 5, 1, 1))
graphics::image(
  1:length(nuc.color), 1, as.matrix(1:length(nuc.color)),
  col = nuc.color,
  xlab = "", ylab = "", xaxt = "n", yaxt = "n", bty = "n"
)
graphics::text(1:length(nuc.color), 1, names(nuc.color))
graphics::mtext(
  text = "Base", adj = 1, las = 1,
  side = 2
)

Default color scheme for amino acid annotation is from Residual colours: a proposal for aminochromography:

aa.color = c(
  "D" = "#FF0000", "S" = "#FF2400", "T" = "#E34234", "G" = "#FF8000", "P" = "#F28500",
  "C" = "#FFFF00", "A" = "#FDFF00", "V" = "#E3FF00", "I" = "#C0FF00", "L" = "#89318C",
  "M" = "#00FF00", "F" = "#50C878", "Y" = "#30D5C8", "W" = "#00FFFF", "H" = "#0F2CB3",
  "R" = "#0000FF", "K" = "#4b0082", "N" = "#800080", "Q" = "#FF00FF", "E" = "#8F00FF",
  "*" = "#FFC0CB", " " = "#FFFFFF", " " = "#FFFFFF", " " = "#FFFFFF", " " = "#FFFFFF"
)

graphics::par(mar = c(1, 5, 1, 1))
graphics::image(
  1:5, 1:5, matrix(1:length(aa.color),nrow=5),
  col = rev(aa.color),
  xlab = "", ylab = "", xaxt = "n", yaxt = "n", bty = "n"
)
graphics::text(expand.grid(1:5,1:5), names(rev(aa.color)))
graphics::mtext(
  text = "Amino acids", adj = 1, las = 1,
  side = 2
)

Add base and amino acid annotation

ggcoverage(data = track.df, color = "grey", range.position = "out", single.nuc=T, rect.color = "white") +
  geom_base(bam.file = bam.file,
            bs.fa.seq = BSgenome.Hsapiens.UCSC.hg19) +
  geom_ideogram(genome = "hg19",plot.space = 0)
#> Loading ideogram...
#> Loading ranges...
#> Scale for 'x' is already present. Adding another scale for 'x', which will
#> replace the existing scale.

ChIP-seq data

The ChIP-seq data used here are from DiffBind, I select four sample to use as example: Chr18_MCF7_input, Chr18_MCF7_ER_1, Chr18_MCF7_ER_3, Chr18_MCF7_ER_2, and all bam files are converted to bigwig file with deeptools.

Create metadata:

# load metadata
sample.meta = data.frame(SampleName=c('Chr18_MCF7_ER_1','Chr18_MCF7_ER_2','Chr18_MCF7_ER_3','Chr18_MCF7_input'),
                         Type = c("MCF7_ER_1","MCF7_ER_2","MCF7_ER_3","MCF7_input"),
                         Group = c("IP", "IP", "IP", "Input"))
sample.meta
#>         SampleName       Type Group
#> 1  Chr18_MCF7_ER_1  MCF7_ER_1    IP
#> 2  Chr18_MCF7_ER_2  MCF7_ER_2    IP
#> 3  Chr18_MCF7_ER_3  MCF7_ER_3    IP
#> 4 Chr18_MCF7_input MCF7_input Input

Load track files:

# track folder
track.folder = system.file("extdata", "ChIP-seq", package = "ggcoverage")
# load bigwig file
track.df = LoadTrackFile(track.folder = track.folder, format = "bw",
                         meta.info = sample.meta)
# check data
head(track.df)
#>   seqnames    start      end   score      Type Group
#> 1    chr18 76799701 76800000 439.316 MCF7_ER_1    IP
#> 2    chr18 76800001 76800300 658.974 MCF7_ER_1    IP
#> 3    chr18 76800301 76800600 219.658 MCF7_ER_1    IP
#> 4    chr18 76800601 76800900 658.974 MCF7_ER_1    IP
#> 5    chr18 76800901 76801200   0.000 MCF7_ER_1    IP
#> 6    chr18 76801201 76801500 219.658 MCF7_ER_1    IP

Prepare mark region:

# create mark region
mark.region=data.frame(start=c(76822533),
                       end=c(76823743),
                       label=c("Promoter"))
# check data
mark.region
#>      start      end    label
#> 1 76822533 76823743 Promoter

Basic coverage

basic.coverage = ggcoverage(data = track.df, color = "auto", region = "chr18:76822285-76900000", 
                            mark.region=mark.region, show.mark.label = FALSE)
basic.coverage

Add annotations

Add gene, ideogram and peak annotations. To create peak annotation, we first get consensus peaks with MSPC.

# get consensus peak file
peak.file = system.file("extdata", "ChIP-seq", "consensus.peak", package = "ggcoverage")

basic.coverage +
  geom_gene(gtf.gr=gtf.gr) +
  geom_peak(bed.file = peak.file) +
  geom_ideogram(genome = "hg19",plot.space = 0)
#> Loading ideogram...
#> Loading ranges...
#> Scale for 'x' is already present. Adding another scale for 'x', which will
#> replace the existing scale.

Code of Conduct

Please note that the ggcoverage project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.