Calculate group mean (or other summary stats) and assign to original data

Question

I want to calculate mean (or any other summary statistics of length one, e.g. min, max, length, sum) of a nu

Answer 1

Have a look at the ave function. Something like

df$grp.mean.values <- ave(df$value, df$group)

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If you want to use ave to calculate something else per group, you need to specify FUN = your-desired-function, e.g. FUN = min:

df$grp.min <- ave(df$value, df$group, FUN = min)