Change row order in a matrix/dataframe

Question

I need to change/invert rows in my data frame, not transposing the data but moving the bottom row to the top and so on. If the data frame was:

1 2 3 
4 5 6
7         


        

Answer 1

We can reverse the order of row.names (for data.frame only):

# create data.frame
m <- matrix(1:9, ncol=3, byrow=TRUE)
df_m <- data.frame(m)

#reverse
df_m[rev(rownames(df_m)), ]

#   X1 X2 X3
# 3  7  8  9
# 2  4  5  6
# 1  1  2  3