数字作为字符串参与循环时，循环怎么写？

以下代码，我想改写成循环(最终输出为.xlsx)时，遇到了问题....请问能不能有大佬能帮帮小白....万谢...

markers.00 <- FindConservedMarkers(obj, ident.1 = "0", grouping.var = "Group", verbose = FALSE)
markers.01 <- FindConservedMarkers(obj, ident.1 = "1", grouping.var = "Group", verbose = FALSE)
markers.02 <- FindConservedMarkers(obj, ident.1 = "2", grouping.var = "Group", verbose = FALSE)
markers.03 <- FindConservedMarkers(obj, ident.1 = "3", grouping.var = "Group", verbose = FALSE)
markers.04 <- FindConservedMarkers(obj, ident.1 = "4", grouping.var = "Group", verbose = FALSE)
markers.05 <- FindConservedMarkers(obj, ident.1 = "5", grouping.var = "Group", verbose = FALSE)
markers.06 <- FindConservedMarkers(obj, ident.1 = "6", grouping.var = "Group", verbose = FALSE)
markers.07 <- FindConservedMarkers(obj, ident.1 = "7", grouping.var = "Group", verbose = FALSE)
markers.08 <- FindConservedMarkers(obj, ident.1 = "8", grouping.var = "Group", verbose = FALSE)
markers.09 <- FindConservedMarkers(obj, ident.1 = "9", grouping.var = "Group", verbose = FALSE)
markers.10 <- FindConservedMarkers(obj, ident.1 = "10", grouping.var = "Group", verbose = FALSE)
markers.11 <- FindConservedMarkers(obj, ident.1 = "11", grouping.var = "Group", verbose = FALSE)
markers.12 <- FindConservedMarkers(obj, ident.1 = "12", grouping.var = "Group", verbose = FALSE)
markers.13 <- FindConservedMarkers(obj, ident.1 = "13", grouping.var = "Group", verbose = FALSE)
markers.14 <- FindConservedMarkers(obj, ident.1 = "14", grouping.var = "Group", verbose = FALSE)
markers.15 <- FindConservedMarkers(obj, ident.1 = "15", grouping.var = "Group", verbose = FALSE)
write_xlsx(list("0"=markers.00,"1"=markers.01,"2"=markers.02,"3"=markers.03,"4"=markers.04,"5"=markers.05,"6"=markers.06,"7"=markers.07,"8"=markers.08,"9"=markers.09,"10"=markers.10,"11"=markers.11,"12"=markers.12,"13"=markers.13,"14"=markers.14,"15"=markers.15), "marker conserved.xlsx")


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我的问题是 ident.1 = " "里面的0~15，其实是字符串，所以 ident.1 =”[]"不可行。
我尝试：
markers.=list()
cluster=list("0","1","2","3","4","5","6","7","8","9","10")
for (i in 1:16){
  markers.[[i-1]] <- FindConservedMarkers(obj, ident.1 = cluster[], grouping.var = "Group", verbose = FALSE)
}

报错错误: 找不到对象'i'
请教正确的做法........

顶一下。。。。