根据其他分类值添加一列因子

Question

I have a massive dataset, and I want to add a factor to each value based on another factor. Currently, my data look like this:

     Type      Value
 1   Wild      68.51
 2   Wild      91.94
 3   Captive   72.58
 4   Hybrid    85.38

But I want to add another column of factors - {Australia, Costa Rica, Brazil} - that is based on if animals are wild, captive or hybrids. The data frame should then look like this:

     Type      Value    Status
 1   Wild      68.51    Costa Rica
 2   Wild      91.94    Costa Rica
 3   Captive   72.58    Australia
 4   Hybrid    85.38    Brazil 

Answer 1

Something like this using dplyr::case_when ?

library(dplyr);
df %>%
    mutate(Status = case_when(
        Type == "Wild" ~ "Costa Rica",
        Type == "Captive" ~ "Australia",
        Type == "Hybrid" ~ "Brazil"));
#     Type Value     Status
#1    Wild 68.51 Costa Rica
#2    Wild 91.94 Costa Rica
#3 Captive 72.58  Australia
#4  Hybrid 85.38     Brazil

---

Sample data

df <- read.table(text =
    "Type      Value
    1   Wild      68.51
    2   Wild      91.94
    3   Captive   72.58
    4   Hybrid    85.38", header = T)

Answer 2

A base R option would be to create a named vector as key/value pairs and use that to match the column 'Type'

df$Status <- setNames( c('Costa Rica', 'Australia', 'Brazil'), 
            c('Wild', 'Captive', 'Hybrid'))[as.character(df$Type)]
df
#      Type Value     Status
#1    Wild 68.51 Costa Rica
#2    Wild 91.94 Costa Rica
#3 Captive 72.58  Australia
#4  Hybrid 85.38     Brazil