TSさんの<mergeするとカバレージ倍増。>というのは以下の説明だね。
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Merged BAM File
A set of BAM files can now be loaded merged into a single track. If each file contains different Sample or Read Group tags, as specified in the SAM/BAM file format, then the merged track can be sorted by these to differentiate the origins of reads to these files within a single track.
Create a text file containing a list of the BAM files you want to load, listed by either file path or URL. IGV will load all the BAM files as a single track.
This file must be in plain text format with .txt extension. Rich text format will cause an error.
For older versions of IGV, be sure there is not an extra line at the bottom of the list. This causes an error.
If IGV gives an error "Error loading.... Cannot find reader for alignment file" see here.
Required Extension: .bam.list
