Sort matrix or data frame

A useful function for ranking. Sort matrix or dataframe 'Mat', by column(s) 'Sort' in decrising or increasing order.

Usage

sortmat (Mat, Sort, decreasing=FALSE)

Arguments

Mat

a matrix or a data frame

Sort

Sort is a number !

decreasing

in decreasing order? default: FALSE

Value

sorted matrix or data frame

Author

found in world wide web: http://tolstoy.newcastle.edu.au/R/help/99b/0668.html

Examples

m <- matrix(c(9:5, c(1, 4, 3, 3, 5), c(1, 2, 4, 3, 5)), ncol = 3, byrow = FALSE)

print( m)
#>      [,1] [,2] [,3]
#> [1,]    9    1    1
#> [2,]    8    4    2
#> [3,]    7    3    4
#> [4,]    6    3    3
#> [5,]    5    5    5
#    [,1] [,2] [,3]
#[1,]    9    1    1
#[2,]    8    4    2
#[3,]    7    3    4
#[4,]    6    3    3
#[5,]    5    5    5

# sort first according to the second column then if equal according to the third column 
print(m1 <- sortmat(Mat = m, Sort = c(2, 3)))
#>      [,1] [,2] [,3]
#> [1,]    9    1    1
#> [2,]    6    3    3
#> [3,]    7    3    4
#> [4,]    8    4    2
#> [5,]    5    5    5
#     [,1] [,2] [,3]
#[1,]    9    1    1
#[2,]    6    3    3
#[3,]    7    3    4
#[4,]    8    4    2
#[5,]    5    5    5


# sort first according to the third (!)  column then if equal according
# to the second column 
print(m2 <- sortmat(Mat = m, Sort = c(3, 2)))
#>      [,1] [,2] [,3]
#> [1,]    9    1    1
#> [2,]    8    4    2
#> [3,]    6    3    3
#> [4,]    7    3    4
#> [5,]    5    5    5
#     [,1] [,2] [,3]
#[1,]    9    1    1
#[2,]    8    4    2
#[3,]    6    3    3
#[4,]    7    3    4
#[5,]    5    5    5

# Note m1 and m2 are not equal!!!!
all(m1==m2) #FALSE
#> [1] FALSE


# in decreasing order
print(m3 <- sortmat(Mat = m, Sort = c(2, 3), decreasing=TRUE))
#>      [,1] [,2] [,3]
#> [1,]    5    5    5
#> [2,]    8    4    2
#> [3,]    7    3    4
#> [4,]    6    3    3
#> [5,]    9    1    1
#     [,1] [,2] [,3]
#[1,]    5    5    5
#[2,]    8    4    2
#[3,]    7    3    4
#[4,]    6    3    3
#[5,]    9    1    1