Matrix Manipulation Tools

Converts a matrix to a list, calculates matrix fill, or exclude rows/columns with certain rox/column sums.

Usage

mat2list(x, MARGIN = 1)
mfill(x)
rdrop(x, cutoff = 0, attrib = FALSE)
cdrop(x, cutoff = 0, attrib = FALSE)

Arguments

x

A vector or matrix to be converted. cdrop and rdrop can take mefa objects as argument.

MARGIN

Margin in c(1, 2), indicating respectively rows or colums to be listed.

cutoff

Numeric, exclude rows/columns with sums <= cutoff.

attrib

Logical, if a vector of excluded rows/columns should be attached to the return value as an attribute.

Value

mat2list returns a list of length nrow(x) or ncol(x) depending on MARGIN. Elements are rows/columns of x. Dimnames are retained as names.

mfill returns a single number with the matrix fill value.

rdrop and cdrop returns the original object but excluding rows (rdrop), or columns (cdrop) that has sum <= cutoff. Excluded row/colum numbers and specifications are stored in the "exclude" attribute of attrib = TRUE.

References

S\'olymos P. (2008) mefa: an R package for handling and reporting count data. Community Ecology 9, 125--127.

S\'olymos P. (2009) Processing ecological data in R with the mefa package. Journal of Statistical Software 29(8), 1--28. doi:10.18637/jss.v029.i08

http://mefa.r-forge.r-project.org/

Author

P\'eter S\'olymos, solymos@ualberta.ca

Examples

x <- matrix(1:12, 3, 4)
rownames(x) <- letters[1:3]
colnames(x) <- LETTERS[1:4]
mat2list(x, 1)
#> $a
#>  A  B  C  D 
#>  1  4  7 10 
#> 
#> $b
#>  A  B  C  D 
#>  2  5  8 11 
#> 
#> $c
#>  A  B  C  D 
#>  3  6  9 12 
#> 
mat2list(x, 2)
#> $A
#> a b c 
#> 1 2 3 
#> 
#> $B
#> a b c 
#> 4 5 6 
#> 
#> $C
#> a b c 
#> 7 8 9 
#> 
#> $D
#>  a  b  c 
#> 10 11 12 
#> 
x[2, ] <- 0
x[, 2] <- 0
mfill(x)
#> [1] 0.5
mfill(x) == sum(x > 0) / prod(dim(x))
#> [1] TRUE
rdrop(x)
#>   A B C  D
#> a 1 0 7 10
#> c 3 0 9 12
cdrop(x)
#>   A C  D
#> a 1 7 10
#> b 0 0  0
#> c 3 9 12
cdrop(x, cutoff = 5)
#>   C  D
#> a 7 10
#> b 0  0
#> c 9 12
cdrop(x, cutoff = 22) # be careful
#>  
#> a
#> b
#> c