Splits the values in a numeric matrix column-wise into sequences of non-missing values.
split_by_NAs(x)A vector or matrix.
A matrix containing a column for each run of non-missing values in
x. The number of rows is equal to the longest run of non-missing
values in x and will therefore be at most nrow{x}. The
matrix is padded with NA values at the end of each column, where
necessary.
The returned object has an attribute called split_by_NAs_done
whose value is TRUE, so that in programming one can avoid calling
split_by_NAs more than once.
For each column in x, split_by_NAs finds runs of
values that contain no missing values and assigns them to a column in the
matrix that is returned. Different columns are treated separately.
If there are no missing values in a column then that column appears
unmodified in the output matrix. Please see the Examples
for illustrations.
# Create a simple numeric matrix and insert some NAs
x <- matrix(1:50, 10, 5)
x[c(3, 8), 1] <- NA
x[c(1:2, 5, 10), 3] <- NA
x[1:3, 4] <- NA
x[7:10, 5] <- NA
x
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] 1 11 NA NA 41
#> [2,] 2 12 NA NA 42
#> [3,] NA 13 23 NA 43
#> [4,] 4 14 24 34 44
#> [5,] 5 15 NA 35 45
#> [6,] 6 16 26 36 46
#> [7,] 7 17 27 37 NA
#> [8,] NA 18 28 38 NA
#> [9,] 9 19 29 39 NA
#> [10,] 10 20 NA 40 NA
res <- split_by_NAs(x)
res
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
#> [1,] 1 4 9 11 23 26 34 41
#> [2,] 2 5 10 12 24 27 35 42
#> [3,] NA 6 NA 13 NA 28 36 43
#> [4,] NA 7 NA 14 NA 29 37 44
#> [5,] NA NA NA 15 NA NA 38 45
#> [6,] NA NA NA 16 NA NA 39 46
#> [7,] NA NA NA 17 NA NA 40 NA
#> [8,] NA NA NA 18 NA NA NA NA
#> [9,] NA NA NA 19 NA NA NA NA
#> [10,] NA NA NA 20 NA NA NA NA
#> attr(,"split_by_NAs_done")
#> [1] TRUE
# An example of a character matrix
x <- matrix(c(letters, letters[1:18]), 11, 4)
x[c(1:2, 5:11), 2] <- NA
x[c(2:4, 6:11), 3] <- NA
x[1:10, 4] <- NA
res <- split_by_NAs(x)
res
#> [,1] [,2] [,3] [,4] [,5]
#> [1,] "a" "n" "w" "a" "r"
#> [2,] "b" "o" NA NA NA
#> [3,] "c" NA NA NA NA
#> [4,] "d" NA NA NA NA
#> [5,] "e" NA NA NA NA
#> [6,] "f" NA NA NA NA
#> [7,] "g" NA NA NA NA
#> [8,] "h" NA NA NA NA
#> [9,] "i" NA NA NA NA
#> [10,] "j" NA NA NA NA
#> [11,] "k" NA NA NA NA
#> attr(,"split_by_NAs_done")
#> [1] TRUE