How to divide value by max column for positive and negative data-CodePudding

I have a short matrix that represents in the below line:

I want to get x/max(x) for the positive value and x/min(x) for the negative value. the result column which wanted to obtain هt is as follows:

    a.max    b.max
      1/5     2/3
      5/5    -6/6
     -3/3    -4/6
      4/5     3/3

Note: To get the minimum, I have to make the number below the fraction positive

CodePudding user response：

How about this:

mat <- matrix(c(1,5,-3,4,2,-6,-4,3), ncol=2)

If you want it to do the division

apply(mat, 2, function(x)x/ifelse(x < 0, abs(min(x)), abs(max(x))))
#>      [,1]       [,2]
#> [1,]  0.2  0.6666667
#> [2,]  1.0 -1.0000000
#> [3,] -1.0 -0.6666667
#> [4,]  0.8  1.0000000

If you don't want it to do the math, if you want it to print the string.

apply(mat, 2, function(x)paste(x, "/", ifelse(x < 0, abs(min(x)), abs(max(x))), sep=""))
#>      [,1]   [,2]  
#> [1,] "1/5"  "2/3" 
#> [2,] "5/5"  "-6/6"
#> [3,] "-3/3" "-4/6"
#> [4,] "4/5"  "3/3"

^{Created on 2022-12-08 by the reprex package (v2.0.1)}

CodePudding user response：

Rewriting and slightly modifying @DaveArmstrong's solution using dplyr, we can have this:

Data and Package

library(dplyr)

m <- tibble::tribble(
  ~a, ~b,
   1,   2,
   5,  -6,
  -3,  -4,
   4,   3
)

m
#> # A tibble: 4 × 2
#>       a     b
#>   <dbl> <dbl>
#> 1     1     2
#> 2     5    -6
#> 3    -3    -4
#> 4     4     3

(1) Solution as number

m %>% mutate(across(a:b, ~.x/ifelse(.x < 0, abs(min(.x)), abs(max(.x)))))

#> # A tibble: 4 × 2
#>       a      b
#>   <dbl>  <dbl>
#> 1   0.2  0.667
#> 2   1   -1    
#> 3  -1   -0.667
#> 4   0.8  1

(2) Solution as formula (character)

m %>% mutate(across(a:b, ~paste0(.x, "/", ifelse(.x < 0, abs(min(.x)), abs(max(.x))))))

#> # A tibble: 4 × 2
#>   a     b    
#>   <chr> <chr>
#> 1 1/5   2/3  
#> 2 5/5   -6/6 
#> 3 -3/3  -4/6 
#> 4 4/5   3/3

^{Created on 2022-12-08 with reprex v2.0.2}