Shifting non-NA cells to the left

问题

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.

回答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>

回答2:

Thanks to @Richard Scriven for good observation

A) with is.na and order, lapply and rbind for aggregation

nosort.df<-do.call(rbind,lapply(1:nrow(df),function(x) { z=df[x,][order(is.na(df[x,]))];colnames(z)<-c("x","y","z");return(z) } ))

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

B) if sorted rows are required:

with sort, lapply and rbind

sort.df<-do.call(rbind,lapply(1:nrow(df),function(x) { z=sort(df[x,],na.last=TRUE);colnames(z)<-c("x","y","z");return(z) } ))

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

回答3:

If you won't get shorter answer, this should help:

df=data.frame(x=c("l","m",NA,NA,"p"),y=c(NA,"b","c",NA,NA),z=c("u",NA,"w","x","y"))
sapply(df,as.character)


for(i in 1:nrow(df)){
  sub <- df[i,c(which(!is.na(df[i,])),which(is.na(df[i,])))] 
  colnames(sub) <- colnames(df)
  df[i,] <- sub
}

回答4:

Another answer with shorter syntax:

df=data.frame(x=c("l","m",NA,NA,"p"),y=c(NA,"b","c",NA,NA),z=c("u",NA,"w","x","y"))

      x   y   z  
[1,] "l" NA  "u"
[2,] "m" "b" NA 
[3,] NA  "c" "w"
[4,] NA  NA  "x"
[5,] "p" NA  "y"



sorted.df <- as.data.frame(t(apply(df, 1, function(x) x[order(is.na(x))])))

     [,1] [,2] [,3]
[1,] "l"  "u"  NA  
[2,] "m"  "b"  NA  
[3,] "c"  "w"  NA  
[4,] "x"  NA   NA  
[5,] "p"  "y"  NA

回答5:

If you don't want to use VBA, you can try the following steps.

1. Select your dataset
2. Replace NA will empty cells
3. press F5 and select blanks ok
4. right click on any of the selection and delete (left)

I hope this helps.

来源：https://stackoverflow.com/questions/23285215/shifting-non-na-cells-to-the-left

标签

dataframe

data-manipulation