合并相同列

            <el-table
              stripe
              v-show="showTable"
              :key="Math.random()"
              v-loading="loading"

　　　　　　　　:span-method="objectSpanMethod"

              :data="selectTableData"
　　　　　　　　 border
              :header-cell-style="{background:'#ffffff',color:'#212529'}"
              empty-text="请选择一个分析"
            >
              <el-table-column
                prop="contract_id"
                label="合同号"
                width="150"
              />

//查找相同列
    rowspan() {
        let position = 0;
        let spanArr = []
      this.selectTableData.forEach((item, index) => {
        if (index === 0) {
          spanArr.push(1);
        } else {
          if (item.contract_id === this.selectTableData[index - 1].contract_id) {
            spanArr[position] += 1;
            spanArr.push(0);
          } else {
            spanArr.push(1);
            position = index;
          }
        }
      });
        return {one:spanArr}
    },

    // 合并相同列
    objectSpanMethod({row, column, rowIndex, columnIndex}) {
      //表格合并第一列
      if (columnIndex === 0) {
        const _row = this.rowspan().one[rowIndex];
        const _col = _row > 0 ? 1 : 0;
        return {
          rowspan: _row,
          colspan: _col
        };
      }


    },