Entering edit mode
>macs_peak <- system.file("extdata", 'H820_OsiR_1_peaks.xls', package = "ChIPpeakAnno")`
> macs_peak
[1] ""
> macs_peak_gr <- toGRanges(macs_peak, format = "MACS")
Error in read.table(data, header = header, comment.char = comment.char, :
system.file can not work
Where is there a reference to this file? Indeed this file does not exist in this package.