What is the error in this code and how can I fix it. This code works for my class mates but won't run properly for me. Im trying to calculate some Anova calculations in R.

df-data. frame Y=C(11, 13, 9, 16, 22, 23, 19, 13, 21, 13, 14, 15), Field=c("A", "A", "A", "B", "B", "B", "C", "C", "C", "D", "D", "D",) df$M mean(df$Y) df$F = NA for(x in levels factor df$Field)) { df [df$Field=-X,]$F = mean(df [df$Field=-X,]$Y) } df$MY df$MF df$FY dfSM - df$Y df SM df$F df$F - df$Y + : > df=data.frame( + Y=C(11, 13, 9, 16, 22, 23, 19, 13, 21, 13, 14, 15), Field=c("A", "A", "A", "B", "B", "B", "C", "C", "C", "D", "D", "D",) Error in data.frame(Y = C(11, 13, 9, 16, 22, 23, 19, 13, 21, 13, 14, 15), argument is missing, with no default > df$M = mean(df$Y) Error in df$Y : object of type 'closure' is not subsettable > df$F = NA Error in df$F = NA : object of type 'closure' is not subsettable + > forX in levels(factor(df$Field)) { df[df$Field==X,]$F = mean(df[df$Field==X,]SY) + } Error: object of type 'closure' is not subsettable > df$MY = df$M - df$Y Error in df$M : object of type 'closure' is not subsettable > df$MF = df$M - df$F Error in df$M : object of type 'closure' is not subsettable > df$FY = df$F - df$Y Error in df$F : object of type 'closure' is not subsettable