data = read.table("clipboard", header = T, sep = '\t')
data
is.data.frame(data)#显示为TRUE
sapply(data,mean,na.rm=T)#报错 >

mean(当日销售,na.rm=T)
[1] NA
Warning message:
In mean.default(当日销售, na.rm = T) :
  argument is not numeric or logical: returning NA

tapply(当日销售,星期,mean,na.rm=T)#报错
> tapply(当日销售,星期,mean,na.rm=T)
1  2  3  4  5  6  7
NA NA NA NA NA NA NA
Warning messages:
1: In mean.default(X[[1L]], ...) :
  argument is not numeric or logical: returning NA
2: In mean.default(X[[2L]], ...) :
  argument is not numeric or logical: returning NA
3: In mean.default(X[[3L]], ...) :
  argument is not numeric or logical: returning NA
4: In mean.default(X[[4L]], ...) :
  argument is not numeric or logical: returning NA
5: In mean.default(X[[5L]], ...) :
  argument is not numeric or logical: returning NA
6: In mean.default(X[[6L]], ...) :
  argument is not numeric or logical: returning NA
7: In mean.default(X[[7L]], ...) :
  argument is not numeric or logical: returning NA


求大神吧帮忙啊！