r - Shifting non-NA cells to the left

Question

There are many NA's in my dataset and I need to shift all those cells (at row level) to the left.

Example- my dataframe:

    df=data.frame(x=c("l","m",NA,NA,"p"),y=c(NA,"b","c",NA,NA),z=c("u",NA,"w","x","y"))
    df
         x    y    z
    1    l <NA>    u
    2    m    b <NA>
    3 <NA>    c    w
    4 <NA> <NA>    x
    5    p <NA>    y

I want the above dataframe converted into this:

      x    y  z
    1 l    u NA
    2 m    b NA
    3 c    w NA
    4 x <NA> NA
    5 p    y NA

Please help.

Thanks.

Answer 1

You can use the standard apply function:

df=data.frame(x=c("l","m",NA,NA,"p"),y=c(NA,"b","c",NA,NA),z=c("u",NA,"w","x","y"))
df2 = as.data.frame(t(apply(df,1, function(x) { return(c(x[!is.na(x)],x[is.na(x)]) )} )))
colnames(df2) = colnames(df)

> df
     x    y    z
1    l <NA>    u
2    m    b <NA>
3 <NA>    c    w
4 <NA> <NA>    x
5    p <NA>    y
> df2
  x    y    z
1 l    u <NA>
2 m    b <NA>
3 c    w <NA>
4 x <NA> <NA>
5 p    y <NA>