[R] Merging matrices of different rows

[Rui Barradas]

Às 11:46 de 26/06/2025, Steven Yen escreveu:
> I'd like to cbind matrices of different number of rows, with missing values filled by "NA". I used dplyr. The following is obviously not working. Help appreciated.
> 
>> library(dplyr)
>> a<-matrix(1:12,nrow=6); a
>       [,1] [,2]
> [1,]    1    7
> [2,]    2    8
> [3,]    3    9
> [4,]    4   10
> [5,]    5   11
> [6,]    6   12
>> b<-matrix(5:12,nrow=4); b
>       [,1] [,2]
> [1,]    5    9
> [2,]    6   10
> [3,]    7   11
> [4,]    8   12
>> cbind.fill(a,b)
> Error in cbind.fill(a, b) : could not find function "cbind.fill"
> 
> Steven from iPhone
> 	[[alternative HTML version deleted]]
> 
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> and provide commented, minimal, self-contained, reproducible code.
Hello,

The error message says that though you have dplyr loaded, R cannot find 
cbind.ill. This means that that function is not a dplyr function.
A google search found rowr::cbind.fill but package rowr is not available 
for R 4.5.0. Abandonware?

Program your own cbind.fill.



cbind.fill <- function(...) {
   dots <- list(...)
   i <- sapply(dots, \(x) inherits(x, "matrix"))
   dots <- dots[i]
   mx <- max(sapply(dots, nrow))
   out_list <- lapply(dots, \(x) {
     if(nrow(x) < mx)
       x <- rbind(x, matrix(nrow = mx - nrow(x), ncol = ncol(x)))
     x
   })
   do.call(cbind, out_list)
}

a<-matrix(1:12,nrow=6)
b<-matrix(5:12,nrow=4)

cbind.fill(a, b)
#>      [,1] [,2] [,3] [,4]
#> [1,]    1    7    5    9
#> [2,]    2    8    6   10
#> [3,]    3    9    7   11
#> [4,]    4   10    8   12
#> [5,]    5   11   NA   NA
#> [6,]    6   12   NA   NA
cbind.fill(b, a, b)
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]    5    9    1    7    5    9
#> [2,]    6   10    2    8    6   10
#> [3,]    7   11    3    9    7   11
#> [4,]    8   12    4   10    8   12
#> [5,]   NA   NA    5   11   NA   NA
#> [6,]   NA   NA    6   12   NA   NA
cbind.fill(b, a, b, a[1:5, ])
#>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
#> [1,]    5    9    1    7    5    9    1    7
#> [2,]    6   10    2    8    6   10    2    8
#> [3,]    7   11    3    9    7   11    3    9
#> [4,]    8   12    4   10    8   12    4   10
#> [5,]   NA   NA    5   11   NA   NA    5   11
#> [6,]   NA   NA    6   12   NA   NA   NA   NA



(Then I found [1], with a version of cbind.fill equivalent to mine.)

[1] https://stackoverflow.com/a/7962286/8245406


Hope this helps,

Rui Barradas



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