R: Find missing columns, add to data frame if missing

Question

I\'d like to write some code that would take a given data frame, check to see if any columns are missing, and if so, add the missing columns filled with 0 or NA. Here\'s wha

Answer 1

library(stringr)
df <- data.frame(X1=1:4,X2=1:4,X5=1:4)
>df
  X1 X2 X5
1  1  1  1
2  2  2  2
3  3  3  3
4  4  4  4
current <- as.numeric(str_extract(names(df),"[0-9]"))
missing <-seq(min(current),max(current))

df[paste("X",missing[!missing %in% current],sep="")]<-0

>df[,order(colnames(df))]
  X1 X2 X3 X4 X5
1  1  1  0  0  1
2  2  2  0  0  2
3  3  3  0  0  3
4  4  4  0  0  4