SurVirus on unmapped reads only

[MjelleLab]

I have extracted the unmapped reads from the original bam file (which is 100+GB, so I therefore cannot run on all raw files). I want to run SurVirus on this file, is it possible? I have indexed this unmapped file but get the following error:

Traceback (most recent call last):
  File "/mnt/scratch/home/local/user/software/SurVirus/SurVirus/surveyor.py", line 91, in <module>
    max_is_calc.get_max_is_from_bam(cmd_args.host_reference, bam_files, cmd_args.wgs, cmd_args.covered_regions_bed)
  File "/mnt/scratch/home/local/user/software/SurVirus/SurVirus/max_is_calc.py", line 76, in get_max_is_from_bam
    mean_is = int(mean(general_dist))
  File "/mnt/scratch/home/local/user/software/SurVirus/SurVirus/max_is_calc.py", line 11, in mean
    return sum(l)/float(len(l))
ZeroDivisionError: float division by zero