Filtering specific values-CodePudding

I am trying to filter the data shown below.

df<-data.frame(  
        Country=c("Aruba","Aruba","Aruba","Afghanistan","Afghanistan","Afghanistan","Afghanistan","Butan","Butan","Belize"),
        Year=c("2007","2008","2009","2006","2007","2008","2009","2006","2009","2006"),
        Value=c(158,196,NA,156,140,693,854,NA,904,925))
        
df

I want to filter only the last values from each country with values different from NA. In the end I need to have the result as a result shown below

So can anybody help me how to solve this problem?

CodePudding user response：

your_data %>%
  na.omit() %>%
  group_by(Country) %>%
  slice_tail(1) %>%
  ungroup()

CodePudding user response：

Base R solution (using Pipes |> so please make sure your R version >= 4.1):

# Split-apply-combine approach mapping ordering and tail functions 
# over data.frame split into list of data.frames by country: 
# result => data.frame
result <- df[complete.cases(df$Value),] |> 
  (\(x){
    data.frame(
      do.call(
        rbind,
        lapply(
          split(
            x, 
            x$Country
          ),
          function(y){
            tail(
              y[order(y$Year),], 
              1
            )
          }
        )
      ),
      stringsAsFactors = FALSE,
      row.names = NULL
    )
  }
)()

# Print result to console: 
# data.frame => stdout(console)
result