Genome Browser Tracks
pyGenomeTracks INI Configuration
ini
[x-axis] where = top [bigwig_coverage] file = sample.bw title = Coverage height = 3 color = #4DBBD5 min_value = 0 max_value = auto [spacer] height = 0.5 [peaks] file = peaks.bed title = Peaks color = #E64B35 height = 1 display = collapsed [genes] file = genes.gtf title = Genes height = 5 fontsize = 10 style = UCSC color = navy
pyGenomeTracks Command
bash
# Generate track plot
pyGenomeTracks --tracks tracks.ini --region chr1:1000000-2000000 \
--outFileName region.png --dpi 300
# Multiple regions
for region in chr1:1000000-2000000 chr2:5000000-6000000; do
pyGenomeTracks --tracks tracks.ini --region $region \
--outFileName "${region//:/_}.png" --dpi 300
done
pyGenomeTracks Python API
python
import pygenometracks.tracks as pygtk
from pygenometracks import plotTracks
# Programmatic track configuration
tracks = '''
[x-axis]
where = top
[bigwig]
file = coverage.bw
title = ChIP-seq
height = 4
color = #4DBBD5
[bed]
file = peaks.narrowPeak
title = Peaks
height = 1
color = #E64B35
'''
# Write config and plot
with open('tracks.ini', 'w') as f:
f.write(tracks)
# Using command line via subprocess
import subprocess
subprocess.run([
'pyGenomeTracks',
'--tracks', 'tracks.ini',
'--region', 'chr1:1000000-2000000',
'--outFileName', 'output.png',
'--dpi', '300'
])
Track Types
bigWig Coverage
ini
[bigwig] file = signal.bw title = Coverage height = 4 color = #4DBBD5 min_value = 0 max_value = auto number_of_bins = 700 nans_to_zeros = true summary_method = mean # overlay_previous = share-y # For overlaying multiple tracks
BED/narrowPeak
ini
[bed] file = peaks.narrowPeak title = Peaks height = 2 color = #E64B35 display = collapsed # or stacked, interleaved, triangles labels = false # file_type = bed # auto-detected usually [bed_links] file = interactions.bedpe title = Loops height = 3 file_type = links links_type = arcs color = purple line_width = 1
Gene Annotations
ini
[genes] file = genes.gtf title = Genes height = 6 fontsize = 10 style = UCSC # or flybase prefered_name = gene_name merge_transcripts = false color = navy border_color = black # arrow_interval = 2 # Arrow frequency [genes_bed12] file = genes.bed12 title = Transcripts height = 5 fontsize = 8 color = darkblue
Hi-C Matrix
ini
[hic_matrix] file = matrix.cool title = Hi-C height = 10 depth = 1000000 min_value = 0 max_value = 100 transform = log1p colormap = RdYlBu_r show_masked_bins = false
IGV Batch Scripting
bash
# Create batch script cat > igv_batch.txt << 'EOF' new genome hg38 load sample1.bam load peaks.bed snapshotDirectory ./snapshots goto chr1:1000000-2000000 snapshot region1.png goto chr2:5000000-6000000 snapshot region2.png exit EOF # Run IGV in batch mode igv -b igv_batch.txt
IGV Batch Commands
bash
# Common IGV batch commands new # New session genome hg38 # Load genome load file.bam # Load track snapshotDirectory ./out # Set output dir goto chr1:1000000-2000000 # Navigate to region sort base # Sort reads collapse # Collapse tracks expand # Expand tracks squish # Squish display maxPanelHeight 500 # Set panel height snapshot file.png # Take screenshot exit # Exit IGV
Gviz (R)
r
library(Gviz)
library(GenomicRanges)
# Axis track
axTrack <- GenomeAxisTrack()
# Gene track from TxDb
library(TxDb.Hsapiens.UCSC.hg38.knownGene)
txdb <- TxDb.Hsapiens.UCSC.hg38.knownGene
grTrack <- GeneRegionTrack(txdb, chromosome = 'chr1', name = 'Genes')
# Data track from BigWig
dTrack <- DataTrack(range = 'coverage.bw', type = 'h',
chromosome = 'chr1', name = 'Coverage',
col = '#4DBBD5')
# Annotation track from BED
aTrack <- AnnotationTrack(range = 'peaks.bed', name = 'Peaks',
chromosome = 'chr1', fill = '#E64B35')
# Plot tracks
plotTracks(list(axTrack, dTrack, aTrack, grTrack),
from = 1000000, to = 2000000,
chromosome = 'chr1')
# Save to PDF
pdf('tracks.pdf', width = 10, height = 6)
plotTracks(list(axTrack, dTrack, aTrack, grTrack),
from = 1000000, to = 2000000)
dev.off()
Multi-Sample Comparison
ini
# tracks.ini for multiple samples [x-axis] [sample1_bw] file = sample1.bw title = Sample 1 height = 3 color = #4DBBD5 min_value = 0 max_value = 100 [sample2_bw] file = sample2.bw title = Sample 2 height = 3 color = #E64B35 min_value = 0 max_value = 100 overlay_previous = share-y [spacer] height = 0.3 [sample1_peaks] file = sample1_peaks.bed title = S1 Peaks height = 1 color = #4DBBD5 [sample2_peaks] file = sample2_peaks.bed title = S2 Peaks height = 1 color = #E64B35
Publication Export
bash
# High resolution PNG
pyGenomeTracks --tracks tracks.ini --region chr1:1-1000000 \
--outFileName figure.png --dpi 300 --width 40
# PDF for vector graphics
pyGenomeTracks --tracks tracks.ini --region chr1:1-1000000 \
--outFileName figure.pdf --width 40
# SVG for editing
pyGenomeTracks --tracks tracks.ini --region chr1:1-1000000 \
--outFileName figure.svg --width 40
Related Skills
- •alignment-files/bam-statistics - Input BAM processing
- •chip-seq/peak-calling - Peak files for tracks
- •hi-c-analysis/matrix-operations - Hi-C visualization
- •data-visualization/multipanel-figures - Combining track figures