基于delimeter拆分R中的数据帧单元

# some example data
df <- data.frame(Impacted_Systems = c("foo;bar", "foo;bar1;bar2", "foo;bar1;bar2;bar4;bar4"))

library(plyr)
library(reshape2)
split_names <- llply(as.list(df$Impacted_Systems), function(x){
                split_data <- data.frame(rbind(strsplit(x, ";")[[1]]))
                names(split_data) <- paste0("Impacted_Systems", 1:length(strsplit(x, ";")[[1]]))
                split_data
    })


> cbind(df, ldply(split_names))
         Impacted_Systems Impacted_Systems1 Impacted_Systems2
1                 foo;bar               foo               bar
2           foo;bar1;bar2               foo              bar1
3 foo;bar1;bar2;bar4;bar4               foo              bar1
  Impacted_Systems3 Impacted_Systems4 Impacted_Systems5
1              <NA>              <NA>              <NA>
2              bar2              <NA>              <NA>
3              bar2              bar4              bar4