How to move cells with a value row-wise to the left in a dataframe [duplicate]

Answer 1

If you don't mind for loop:

ddf
   X1   X2   X3 X4
x1  a    b   c
x2  d    e
x3  f    g    h  i
x4  j     k  l

nddf = ddf
for(i in 1:nrow(ddf))
 nddf[i,] = sort(ddf[i,], na.last=T)

nddf
   X1 X2   X3   X4
x1  a  b    c 
x2  d  e  
x3  f  g    h    i
x4  j  k    l 

If you do not want to sort:

rowfn = function(rr){
 rr2 = rr; j=1
 for(i in 1:length(rr))    if(!is.na(rr[i])){ rr2[j] = rr[i] ;  j = j+1 } 
 if(j<(length(rr)+1)) for(k in j:length(rr))   rr2[k] = NA
 rr2
 }

ddf
   X1   X2   X3 X4
x1  a    b   c
x2  d    e
x3  f    g    h  i
x4  j     k  l

nddf = ddf
for(i in 1:nrow(ddf)) nddf[i,] = rowfn(ddf[i,])

nddf
   X1 X2   X3   X4
x1  a  b    c 
x2  d  e  
x3  f  g    h    i
x4  j  k    l