我有以下数据集（我从6列的 Excel文件中导入，文件扩展名为.csv）
ExpansionPanel(
headerBuilder:
(BuildContext context, bool isExpanded) {
return ListTile(...);
},
body: Flexible(
child: TimelineComponent(
timelineList: list,
),
),
isExpanded:
_categoryExpansionStateMap["UserMediceneLists"]),
当我在treas <- read.csv(file = 'treas.csv', header = TRUE, stringsAsFactors = FALSE)
2YR 3YR 5YR 7YR 10YR 30YR
0.41 0.85 1.65 2.18 2.6 3.43
0.41 0.85 1.65 2.2 2.61 3.45
0.4 0.82 1.63 2.17 2.59 3.44
0.41 0.86 1.66 2.19 2.6 3.44
0.43 0.88 1.69 2.22 2.62 3.45
0.45 0.93 1.71 2.24 2.64 3.47
0.44 0.91 1.7 2.23 2.65 3.47
0.42 0.88 1.66 2.17 2.58 3.41
0.45 0.93 1.7 2.21 2.6 3.41
0.49 0.95 1.71 2.21 2.61 3.4
0.51 0.99 1.77 2.27 2.66 3.44
0.48 0.95 1.71 2.21 2.61 3.43
0.48 0.94 1.71 2.22 2.64 3.47
0.5 0.94 1.71 2.22 2.63 3.44
0.48 0.96 1.72 2.23 2.63 3.45
0.49 0.95 1.7 2.19 2.59 3.41
0.48 0.92 1.68 2.17 2.57 3.38
0.46 0.9 1.64 2.14 2.53 3.35
0.45 0.88 1.64 2.14 2.54 3.36
0.47 0.88 1.62 2.13 2.53 3.34
0.47 0.9 1.66 2.17 2.58 3.4
0.49 0.95 1.71 2.22 2.64 3.46
0.52 0.98 1.74 2.25 2.65 3.47
0.52 1 1.74 2.24 2.63 3.44
0.51 0.99 1.7 2.19 2.58 3.38
0.51 0.97 1.68 2.17 2.57 3.37
0.46 0.93 1.66 2.15 2.55 3.38
0.48 0.92 1.65 2.13 2.53 3.34
0.48 0.95 1.68 2.17 2.55 3.36
数据帧上调用cov（）方法时，看到以下错误消息：
treas要检查数据类型，请使用：
Error: is.numeric(x) || is.logical(x) is not TRUE
结果是：
sapply(treas, typeof)
呼叫 2YR 3YR 5YR 7YR 10YR 30YR
"character" "character" "character" "character" "character" "character"
会显示：
str(treas)我尝试使用以下方法将数据框强制为数字
str(treas)
'data.frame': 1252 obs. of 6 variables:
$ 2YR : Factor w/ 235 levels ".","0.34","0.35",..: 8 8 7 8 10 12 11 9 12 16 ...
$ 3YR : chr w/ 219 levels ".","0.66","0.69",..: 18 18 15 19 21 26 24 21 26 28 ...
$ 5YR : chr w/ 207 levels ".","0.94","0.95",..: 67 67 65 68 71 73 72 68 72 73 ...
$ 7YR : chr w/ 192 levels ".","1.19","1.20",..: 96 98 95 97 100 102 101 95 99 99 ...
$ 10YR : chr w/ 178 levels ".","1.37","1.38",..: 118 119 117 118 120 122 123 116 118 119 ...
$ 30YR : chr w/ 125 levels ".","2.11","2.14",..: 121 123 122 122 123 125 125 120 120 119 ...
但是，这样做会导致：
lapply(treas, as.numeric)
然后，我在调用Warning messages:
1: In lapply(treas, as.numeric) : NAs introduced by coercion
2: In lapply(treas, as.numeric) : NAs introduced by coercion
3: In lapply(treas, as.numeric) : NAs introduced by coercion
4: In lapply(treas, as.numeric) : NAs introduced by coercion
5: In lapply(treas, as.numeric) : NAs introduced by coercion
6: In lapply(treas, as.numeric) : NAs introduced by coercion
时仍然遇到相同的错误：
cov(treas)有人看到我在这里做错了吗？谢谢！