Add missing value in column with value from row above

Question

Every week I a incomplete dataset for a analysis. That looks like:

df1 <- data.frame(var1 = c(\"a\",\"\",\"\",\"b\",\"\"), 
             var2 = c(\"x\",\"         


        

Answer 1

Here is one way of doing it by making use of run-length encoding (rle) and its inverse rle.inverse:

fillTheBlanks <- function(x, missing=""){
  rle <- rle(as.character(x))
  empty <- which(rle$value==missing)
  rle$values[empty] <- rle$value[empty-1] 
  inverse.rle(rle)
}

df1$var1 <- fillTheBlanks(df1$var1)

The results:

df1

  var1 var2
1    a    x
2    a    y
3    a    z
4    b    x
5    b    z