el-table合并单元格指定行小计、总计

<div>
      <el-table
        :data="tableData"
        :span-method="arraySpanMethod"
        :cell-style="cellStyleMethod"
        border
        style="width: 100%"
      >
        <el-table-column prop="name" label="姓名"> </el-table-column>
        <el-table-column prop="id" label="ID" width="180"> </el-table-column>
        <el-table-column prop="amount1" sortable label="数值 1">
        </el-table-column>
        <el-table-column prop="amount2" sortable label="数值 2">
        </el-table-column>
        <el-table-column prop="amount3" sortable label="数值 3">
        </el-table-column>
      </el-table>
    </div>

data() {
    return {
      tableData: [
        {
          id: '12987122',
          name: '王小虎',
          amount1: 1,
          amount2: '3.2',
          amount3: 10
        },
        {
          id: '12987122',
          name: '王小虎',
          amount1: 1,
          amount2: '3.2',
          amount3: 10
        },
        {
          id: '12987123',
          name: '王小虎',
          amount1: 2,
          amount2: '4.43',
          amount3: 12
        },
        {
          id: '12987124',
          name: '王小二',
          amount1: 3,
          amount2: '1.9',
          amount3: 9
        },
        {
          id: '12987125',
          name: '王小二',
          amount1: 6,
          amount2: '2.2',
          amount3: 17
        },
        {
          id: '12987125',
          name: '王小二',
          amount1: 6,
          amount2: '2.2',
          amount3: 17
        },
        {
          id: '12987126',
          name: '王小三',
          amount1: 4,
          amount2: '4.1',
          amount3: 15
        },
        {
          id: '12987126',
          name: '王小三',
          amount1: 539,
          amount2: '4.1',
          amount3: 15
        },
        {
          id: '12987127',
          name: '王小三',
          amount1: 539,
          amount2: '4.1',
          amount3: 15
        },
        {
          id: '12987127',
          name: '王小三',
          amount1: 539,
          amount2: '4.1',
          amount3: 15
        }
      ],
      spanNameArr: [],
      namePos: '',
      spanIdArr: [],
      idPos: ''
  }
},
mounted() {
  this.formatData()
},

methods: {
    formatData() {
      let data = JSON.parse(JSON.stringify(this.tableData));
      let pos = 0;
      let temp = {};
      for (let i = 0; i < data.length; i++) {
        if (temp[data[i].name]) {
          temp[data[i].name]['amount1'] += parseFloat(data[i].amount1);
        } else {
          temp[data[i].name] = {};
          temp[data[i].name]['amount1'] = parseFloat(data[i].amount1);
        }
        if (i > 0 && data[i].name !== data[i - 1].name) {
          let amount1 = temp[data[i - 1].name]['amount1'];
          this.tableData.splice(i + pos, 0, {
            id: '合计',
            name: '合计',
            amount1: amount1,
            amount2: '3.2',
            amount3: 10
          });
          pos++;
        } else if (i === data.length - 1) {
          let amount1 = temp[data[i - 1].name]['amount1'];
          this.tableData.push({
            id: '合计',
            name: '合计',
            amount1: amount1,
            amount2: '3.2',
            amount3: 10
          });
          pos++;
        }
      }
      let totalAmount1 = 0;

      for (let key in temp) {
        totalAmount1 += parseFloat(temp[key].amount1);
      }
      this.tableData.push({
        id: '总计',
        name: '总计',
        amount1: totalAmount1,
        amount2: '3.2',
        amount3: 10
      });
      this.getSpanArr(this.tableData, this.spanNameArr, this.namePos, 'name');
      this.getSpanArr(this.tableData, this.spanIdArr, this.idPos, 'id');
    },
    cellStyleMethod({ row, column, rowIndex, columnIndex }) {
      if (row.name === '合计' || row.name === '总计') {
        if (columnIndex === 0) {
          return { 'text-align': 'right' };
        }
      }
    },
    arraySpanMethod({ row, column, rowIndex, columnIndex }) {
      if (row.name === '合计' || row.name === '总计') {
        if (columnIndex === 0) {
          return [1, 2];
        } else if (columnIndex === 1) {
          return [0, 0];
        }
      } else {
        if (columnIndex == 0) {
          const _row = this.spanNameArr[rowIndex];
          const _col = _row > 0 ? 1 : 0;
          return {
            // [0,0] 表示这一行不显示， [2,1]表示行的合并数
            rowspan: _row,
            colspan: _col
          };
        }
        if (columnIndex == 1) {
          const _row = this.spanIdArr[rowIndex];
          const _col = _row > 0 ? 1 : 0;
          return {
            // [0,0] 表示这一行不显示， [2,1]表示行的合并数
            rowspan: _row,
            colspan: _col
          };
        }
      }
    },
    getSpanArr(data, temp, pos, label) {
      // data就是我们从后台拿到的数据
      for (let i = 0; i < data.length; i++) {
        if (i === 0) {
          temp.push(1);
          pos = 0;
        } else {
          // 判断当前元素与上一个元素是否相同
          if (data[i][label] === data[i - 1][label]) {
            temp[pos] += 1;
            temp.push(0);
          } else {
            temp.push(1);
            pos = i;
          }
        }
      }
    },
}