history_c = d.historylist
.map((d0, i) => {
if (i < d.historylist.length - 1) {
d0.cn_c = d0.cn_conNum / d.historylist[i + 1].cn_conNum;
d0.wuhan_c = d0.wuhan_conNum / d.historylist[i + 1].wuhan_conNum;
}
return d0;
})
.slice(0, d.historylist.length - 5)