Sly Grogger 25 Sly Grogger 25 - 15 days ago 5
R Question

Replace multiple columns with column mean of non-zero values

I have data like so:

aye <- c(0,0,3,4,5,6)
bee <- c(3,4,0,0,7,8)
see <- c(9,8,3,5,0,0)
df <- data.frame(aye, bee, see)


I am looking for a concise way to create columns based on the mean for each of the columns in the data frame, where zero is kept at zero.

To obtain the mean excluding zero:

df2 <- as.data.frame(t(apply(df, 2, function(x) mean(x[x>0]))))


I can't figure out how to simply replace the values in the column with the mean excluding zero. My approach so far is:

df$aye <- ifelse(df$aye == 0, 0, df2$aye)
df$bee <- ifelse(df$bee == 0, 0, df2$bee)
df$see <- ifelse(df$see == 0, 0, df2$see)


But this gets messy with many variables - would be nice to wrap it up in one function.

Thanks for your help!

Answer

Why can't we just use

data.frame(lapply(dat, function (u) ave(u, u > 0, FUN = mean)))

#  aye bee  see
#1 0.0 5.5 6.25
#2 0.0 5.5 6.25
#3 4.5 0.0 6.25
#4 4.5 0.0 6.25
#5 4.5 5.5 0.00
#6 4.5 5.5 0.00

Note, I used dat rather than df as the name of your data frame. df is a function in R and don't mask it.