下面的运行就有问题，请大神帮忙

> data1 <- c(1,2,3,1,2,1,2,0,0,0,0,0,0,0,1,2,1,0,0,0,0,0,1,2,1,0,0,0,1,4)
> data2 <- NA
> data_total <- data.frame(data1,data2)> len_data <- length(data1)
#目的是把连续5个是0的数进行更改
> for(i in 1:len_data){
+   if(i < 5){
+     data_total$data2 <- data_total$data1
+   }else{
+     if(sum(data_total$data1[(i-4):i])==0){
+       for(j in 1:4){
+         if(data_total$data2[(i+j-4)]>0){
+           data_total$data2[(i+j-4)] <- data_total$data2[(i+j-4)]
+         }else{
+           data_total$data2[(i+j-4)] <- sample(data_total$data1[which(data_total$data1>0)],1)
+         }
+       }
+      
+     }else{
+       data_total$data2 <- data_total$data1
+     }
+   }
+ }


Error in if (data_total$data2[(i + j - 4)] > 0) { :
  missing value where TRUE/FALSE needed
>