r - how to calculate row means in a data frame?

Question

I have a dataframe with 1000 columns and 8 rows, I need to calculate row means.I tried this loop:

final <- as.data.frame(matrix(nrow=8,ncol=1))
for(j in 1:8){
  value<- mean(dataframe[j,])
  final[j,]<-value
}

but got the following error:

In mean.default(df2[j, ]) : argument is not numeric or logical: returning NA

Answer 1

Use the rowMeans() function:

final$mean <- rowMeans(final, na.rm=TRUE)

Note that you should avoid using loops for your everyday R operations. If you want to iterate over all rows yourself, you can use the apply() function like this:

final$mean <- apply(final, 1, function(x) { mean(x, na.rm=TRUE) })