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Accepted
Patricio Moracho
Asked: 2020-09-28 06:32:16 +0800 CST 2020-09-28 06:32:16 +0800 CST

How to build a matrix product of a comparison with a range of values?

  • 772

Let's assume we have a data.framelike the following:

set.seed(2019)
datos <- data.frame(ANO1=sample(1:10, 10, replace = TRUE),
                    ANO2=sample(1:10, 10, replace = TRUE))
datos

   ANO1 ANO2
1     8    8
2     8    7
3     4    3
4     7    2
5     1    7
6     1    7
7     9    1
8     1    8
9     2    4
10    7    5

What I am looking for is to create a matrix with the logical value of comparing if the two columns are less than a certain set of numbers, for example, let's say a range from 1 to 10, taking the first row as a reference, I would like to obtain something like this :

   ANO1 ANO2     1     2     3     4     5     6     7     8     9   10
1     8    8 FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE TRUE

In this case 8they are both less than 10and 9but not less than the rest of the values.

r

1 Answers

  1. Best Answer

    One way that occurs to me is to create a reference matrix to compare, that is, we are going to create a matrix with the 10 "comparables" and the number of rows of the data.frame, that is:

    nr <- nrow(datos)
mref <- matrix(rep(1:10, nr), nrow = nr , byrow = TRUE)
mref

     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1    2    3    4    5    6    7    8    9    10
 [2,]    1    2    3    4    5    6    7    8    9    10
 [3,]    1    2    3    4    5    6    7    8    9    10
 [4,]    1    2    3    4    5    6    7    8    9    10
 [5,]    1    2    3    4    5    6    7    8    9    10
 [6,]    1    2    3    4    5    6    7    8    9    10
 [7,]    1    2    3    4    5    6    7    8    9    10
 [8,]    1    2    3    4    5    6    7    8    9    10
 [9,]    1    2    3    4    5    6    7    8    9    10
[10,]    1    2    3    4    5    6    7    8    9    10

    Having this, and thanks to the fact that the comparisons are actually functions, we could individually compare each column with its reference value:

    a <- `<`(datos$ANO1, mref)
b <- `<`(datos$ANO2, mref)

    Note: I originally thought it wouldn't work, but it's also totally fine to do:

    a <- datos$ANO1 < mref
b <- datos$ANO2 < mref

    And now we simply make sure that both columns are less than the reference value with a &( andlogical matrix), the combination of the results is only for the purpose of verifying the result:

    cbind(datos, a & b)

   ANO1 ANO2     1     2     3     4     5     6     7     8     9   10
1     8    8 FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE TRUE
2     8    7 FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE TRUE
3     4    3 FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE TRUE
4     7    2 FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE TRUE
5     1    7 FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE TRUE
6     1    7 FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE TRUE
7     9    1 FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE
8     1    8 FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE TRUE
9     2    4 FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE TRUE
10    7    5 FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE TRUE
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