Aggregate by factor levels, keeping other variables in the resulting data frame
r
Solution
You need to use `merge` on result of `aggregate` and original `data.frame`
merge(aggregate(value ~ code, dat, min), dat, by = c("code", "value"))
## code value index
## 1 HH11 24.1 023434
## 2 HH45 37.2 3377477
## 3 JL03 20.0 1177777
Problem
I'm trying to calculate the minimum values of a numeric column for each level of a factor, while keeping values of another factor in the resulting data frame. ``` # dummy data dat <- data.frame( code = c("HH11", "HH45", "JL03", "JL03", "JL03", "HH11"), index = c("023434", "3377477", "3388595", "3377477", "1177777", "023434"), value = c(24.1, 37.2, 78.9, 45.9, 20.0, 34.6) ) ``` The result I want is the minimum of `value` for each level of `code`, keeping `index` in the resulting data frame. ``` # result I want: # code value index # 1 HH11 24.1 023434 # 2 HH45 37.2 3377477 # 3 JL03 20.0 1177777 # ddply attempt library(plyr) ddply(dat, ~ code, summarise, val = min(value)) # code val # 1 HH11 24.1 # 2 HH45 37.2 # 3 JL03 20.0 # base R attempt aggregate(value ~ code, dat, min) # code value # 1 HH11 24.1 # 2 HH45 37.2 # 3 JL03 20.0 ```