By Ico

2013-03-04 12:11:55 8 Comments

I have a (fairly long) list of vectors. The vectors consist of Russian words that I got by using the strsplit() function on sentences.

The following is what head() returns:

[1] "модно"     "создавать" "резюме"    "в"         "виде"     

[1] "ты"        "начианешь" "работать"  "с"         "этими"    

[1] "модно"            "называть"         "блогер-рилейшенз" "―"                "начинается"       "задолго"         

[1] "видел" "по"    "сыну," "что"   "он"   

[1] "четырнадцать," "я"             "поселился"     "на"            "улице"        

[1] "широко"     "продолжали" "род."

Note the vectors are of different length.

What I want is to be able to read the first words from each sentence, the second word, the third, etc.

The desired result would be something like this:

    P1              P2           P3                 P4    P5           P6
[1] "модно"         "создавать"  "резюме"           "в"   "виде"       NA
[2] "ты"            "начианешь"  "работать"         "с"   "этими"      NA
[3] "модно"         "называть"   "блогер-рилейшенз" "―"   "начинается" "задолго"         
[4] "видел"         "по"         "сыну,"            "что" "он"         NA
[5] "четырнадцать," "я"          "поселился"        "на"  "улице"      NA
[6] "широко"        "продолжали" "род."             NA    NA           NA

I have tried to just use data.frame() but that didn't work because the rows are of different length. I also tried rbind.fill() from the plyr package, but that function can only process matrices.

I found some other questions here (that's where I got the plyr help from), but those were all about combining for instance two data frames of different size.

Thanks for your help.


@jgarces 2018-09-14 10:35:57

Another option could be to define a function like this (it'd mimic rbind.fill) or use it directly from rowr package:

cbind.fill <- function(...){
  nm <- list(...) 
  nm <- lapply(nm, as.matrix)
  n <- max(sapply(nm, nrow)), lapply(nm, function (x) 
    rbind(x, matrix(, n-nrow(x), ncol(x))))) 


@andschar 2018-03-15 14:21:38

you could also use rbindlist() from data.table-package.

Convert vectors to data.table or data.frame and transpose it (not sure if this reduces speed a lot) with the help of lapply(). Then bind them with rbindlist() - filling missing cells with NA:

l = list(c("a","b","c"), c("a2","b2"), c("a3","b3","c3","d3"))
dt = rbindlist(lapply(l, function(x) data.table(t(x))),
     fill = TRUE)

@akrun 2016-03-17 19:51:39

Another option is stri_list2matrix from library(stringi)

stri_list2matrix(l, byrow=TRUE)
#    [,1] [,2] [,3] [,4]
#[1,] "a"  "b"  "c"  NA  
#[2,] "a2" "b2" NA   NA  
#[3,] "a3" "b3" "c3" "d3"

NOTE: Data from @juba's post.

Or as @Valentin mentioned in the comments

sapply(l, "length<-", max(lengths(l)))

@Valentin 2018-01-26 21:47:12

I think your elegant base R solution given here is worth being mentioned as well: sapply(l, "length<-", max(lengths(l)))

@Ramnath 2013-03-04 15:17:42

One liner with plyr

plyr::ldply(word.list, rbind)

@adibender 2013-03-04 12:32:46

try this:

word.list <- list(letters[1:4], letters[1:5], letters[1:2], letters[1:6])
n.obs <- sapply(word.list, length)
seq.max <- seq_len(max(n.obs))
mat <- t(sapply(word.list, "[", i = seq.max))

the trick is, that,


returns the vector + two NAs

@Arun 2013-03-04 12:40:32

this could be further condensed to one line by: sapply(word.list, '[', seq(max(sapply(word.list, length)))) (as shown here)

@Ashe 2017-03-28 21:12:48

For those who would use @Arun's one-line solution, note that there must be a transpose t() to create the appropriate columns, as in the original question.

@juba 2013-03-04 12:21:10

You can do something like this :

## Example data
l <- list(c("a","b","c"), c("a2","b2"), c("a3","b3","c3","d3"))
## Compute maximum length
max.length <- max(sapply(l, length))
## Add NA values to list elements
l <- lapply(l, function(v) { c(v, rep(NA, max.length-length(v)))})
## Rbind, l)

Which gives :

     [,1] [,2] [,3] [,4]
[1,] "a"  "b"  "c"  NA  
[2,] "a2" "b2" NA   NA  
[3,] "a3" "b3" "c3" "d3"

@Carl Witthoft 2013-03-04 15:33:07

Aha -- what we forgot (Juba and me) is that you don't need to "fill in" the original list elements with NA values. The sapply snippet I put in a comment returns NA for list elements which are shorter than the requested index value. Ain't it nice of sapply not to crash? :-)

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