Proposed method:

Similar to sortBy, but instead of just sorting by the returned value, it will rebuild the list using the returned value as the entry's index for an array of entries. This would be useful when trying to group or categorize.

e.g.

  { pid: '2384',
    name: 'node run',
    exe: 'node.exe',
    path: 'C:\\Program Files\\nodejs\\node.exe',
    cmdline: 'node.exe',
    memuse: '13348864' },
  { pid: '5000',
    name: 'C:\\Windows\\system32\\wbem\\wmiprvse.exe',
    exe: 'wmiprvse.exe',
    path: 'C:\\Windows\\system32\\wbem\\wmiprvse.exe',
    cmdline: 'WmiPrvSE.exe',
    memuse: '6266880' } ]

with a groupBy method, you'd be able to group individual processes by 'exe' - something that nothing else (that I can see) would allow for.