Vuejs v-for with index

gistfile1.html

<div class="col-md-4" v-for="(index, group) in wards" track-by="$index">
  <div class="ibox">
    <div class="ibox-title"><strong>{{ index }}</strong></div>
    <div class="ibox-content">
      <div class="col-md-2 bed" v-for="patient in group">
        <a v-link="" v-if="patient.id" class="bed-default">{{ patient.bed_id }}</a>
      </div>
    </div>
  </div>
</div>