plyr

Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]

by

There are many ways to do this. This answer starts with what is quickly becoming the standard method, but also includes older methods and various other methods from answers to similar questions scattered around this site. tmp <- data.frame(x=gl(2,3, labels=letters[24:25]), y=gl(3,1,6, labels=letters[1:3]), z=c(1,2,3,3,3,2)) Using the tidyverse: The new cool new way to do this is … Read more

How to select the rows with maximum values in each group with dplyr? [duplicate]

by

Try this: result <- df %>% group_by(A, B) %>% filter(value == max(value)) %>% arrange(A,B,C) Seems to work: identical( as.data.frame(result), ddply(df, .(A, B), function(x) x[which.max(x$value),]) ) #[1] TRUE As pointed out in the comments, slice may be preferred here as per @RoyalITS’ answer below if you strictly only want 1 row per group. This answer will … Read more