有偿帮忙，希望大神可以帮帮我代码如下：
province.median<-function(subdata,more.return=TRUE){
  Total.Interval<-aggregate(x=subdata$Exam_Interval,by=list(subdata$Exam_year),FUN=quantile,probs=c(0.025,0.50,0.975),na.rm=TRUE)
  Total.Interval<-as.data.frame(as.matrix(Total.Interval))
  Total.Interval$CI<-apply(Total.Interval,1,function(x) paste(round(as.numeric(x[2]),2),round(as.numeric(x[4]),2),sep="-"))
  names(Total.Interval)[c(1,3,5)]<-c("Year","Median","CI")
  Results<-Total.Interval[,c(1,3,5)]
  if(nrow(Results)<3) return(NULL) else{
  Results$Year<-as.numeric(as.character(Results$Year))
  Diff.Median<-wilcox.test(x=subdata$Exam_Interval[which(subdata$Exam_year==2019)],y=subdata$Exam_Interval[which(subdata$Exam_year==2013)],conf.int = TRUE)
  Trend.C<-summary(lm(Median~Year,Results))$coefficients[2,4]
  print(paste("Trend for Median: ",round(Trend.C,4),sep=""))
  Inc.C<-c(Diff.Median$estimate[1]-Diff.Median$estimate[2],Diff.Median$conf.int[1],Diff.Median$conf.int[2])
  print(paste("Abs Increment for Median: ",round(Diff.Median$estimate[1]-Diff.Median$estimate[2],2)," (",round(Diff.Median$conf.int[1],2),"-",round(Diff.Median$conf.int[2],2),")",sep=""))
  Trend.Inc.C<-c(confint.default(lm(Median~Year,Results))[2,1],summary(lm(Median~Year,Results))$coefficients[2,1],confint.default(lm(Median~Year,Results))[2,2])
  print(paste("Annual Change for Median: ",round(Trend.Inc.C[2],2)," (",round(Trend.Inc.C[1],2),"-",round(Trend.Inc.C[3],2),")",sep=""))
  return(list(Results,Trend.C,Inc.C,Trend.Inc.C))  
  }
}


Error in wilcox.test.default(x = subdata$Exam_Interval[which(subdata$Exam_year ==  :   not enough (non-missing) 'x' observations